Isaac Asimov, in one of the anthologies he edited, mentioned reading some astronomical news back in the early 1960s about neutron stars. Being a science popularizer as well as a science fiction author, he was inspired to write a science essay about neutron stars. This was read by a few people but then more or less forgotten.

Apparently Larry Niven read the same news. But Niven wrote a science fiction story instead, the eponymous "Neutron Star". Which won the 1967 Hugo award for best short story. And made first ballot for the 1967 Nebula award. It was not forgotton, that story has been reprinted zillions of times and indeed is still in print.

Asimov included "Neutron Star" in his anthology. In its preface he ruefully noted if instead of thinking like a science essay writer he had been thinking like a science fiction author, Isaac Asimov might have won the 1976 Hugo.

So, science fiction writers reading this: don't make the Good Doctor's mistake.

Science fiction writers often benefit from using reality as a springboard. For science fiction, the weirder the bit of reality used, the better. As a public service, I offer a random selection of real astronomical items that are anomalous, suspicious, or downright odd. SF writers are encouraged to use these to brainstorm something interesting.

These are offered free of charge, I have no claim no them, no strings are attached.

For good examples of science fiction stories based around accurate astronomy, check out the free online anthology Diamonds in the Sky.

Lunar Ice

In the space environment, water is one of the most valuable things in the universe. You can split it into oxygen and hydrogen and use it for breathing, propellant, and in fuel cells. You can drink it or use it to grow plants and algae in your life support system. It can also be used to shield the crew from space radiation. However, as anybody who has carried a bucket of water knows, it has plenty of mass, which makes it very expensive to ship from Terra into orbit.

Which is why people planning space colonies are so interested in In-Situ Resource Utilization, which in this case is a fancy way of saying "trying to find an ice mine." It would be so much more convenient if the water was already there, so you didn't have to go to the insane expense of importing it.

The closest place to look is Luna. Unfortunately data from the Apollo moon missions suggested that the lunar regolith was drier than an old slab of concrete lying in the Sahara desert. Luna's "day" is 27 or so Terran days long, exposing Luna's surface to the merciless rays of the Sun and baking it to an oven-like temperature of 390°K. Any water-ice on the surface would have evaporated into space a long time ago. Even if an occasional water-ice comet smacked into Luna, the Sun's rays would make it go away.

But wait a minute. What if there were places on Luna that were permanently in shadow? Since there is no appreciable atmosphere, an area in Lunar shadow can drop down to a frigid 35°K. Any comet-ice that landed in such a deep-freeze would be preserved quite nicely.

The walls of lunar craters will provide shadow for part of the lunar day, but eventually the sun will be over head, the shadow will vanish, and the comet ice will evaporate. Except for at the lunar north and south poles. There the angle is steep enough that the sun's rays never penetrate the interior of the craters. See the picture, it shows the illumination of the lunar south pole over an entire lunar day. The dark areas are always dark. Any ice deposited there will still be there, patiently waiting for thirsty lunar colonists.

Lo and behold, it is there!

In In September 2009, India's Chandrayaan-1 space probe got a fleeting glimpse of lunar water-ice. In November 2009, NASA's LCROSS space probe watched as its spent upper stage violently crashed into the lunar south pole at 10,000 km/h, spotting ice crystals in the explosion. Finally in March 2010 the Chandrayaan-1 observed a bit of ice in the lunar north pole, a bit over 600 million tonnes of nearly pure water ice.

The lunar poles are going to be valuable real estate.

Giordano Bruno Crater

On the fine evening of June 18, 1178, five monks at the abbey of the Christ Church of Canterbury in England gazed skyward and saw the Moon blow up.

Hoc anno, die Dominica ante Nativitatem Sancti Johannis Baptistae, post solis occasum, luna prima, signum apparuit mirabile, quinque vel eo amplius viris ex adverso sedentibus. Nam nova luna lucida erat, novitatis suae more cornua protendens ad orientem ; et ecce subito superius cornu in duo divisum est. Ex hujus divisionis medio prosilivit fax ardens, flamam, carbones et scintillas longius proiciens. Corpus interim luna quod inferius erat torquebatur quasi anxie, et, ut eorum verbia utar, qui hoc michi retulerunt et oculis viderunt propriis, ut percussus coluber luna palpitabat. Post hoc rediit in proprium statum. Hanc vicissitudinem duodecies et eo amplius repetiit, videlicet ut ignis tormenta varia sicut praelibatum est sustineret, iterumque in statum rediret priorem. Post bas itaque vidasitudines, a cornu usque in cornu scilicet per longum seminigra facta est. Haec michi qui haec scribo retulerunt viri illi qui suis hoc viderunt oculis, fidem suam vel jusjurandum dare parati, quod in supradictis nichil addiderunt falsitatis.

This year on the Sunday before the Feast of Saint John the Baptist, after sunset when the moon was first seen, a marvellous sign was seen by five or more men sitting facing it. Now, there was a clear new moon, as was usual at that phase, its horns extended to the east; and behold suddenly the upper horn was divided in two. Out of the middle of its division a burning torch sprang, throwing out a long way, flames, coals and sparks. As well, the moon's body which was lower, twisted as though anxious, and in the words of those who told me and had seen it with their own eyes, the moon palpitated like a pummelled snake. After this it returned to its proper state. This vicissitude repeated itself a dozen times or more, namely that the fire took on tormented forms variously at random, and afterwards returned to its prior state. Even after these vicissitudes, from horn to horn, that means along its length, it became semi-black. This to me who writes this was told by those men who with their own eyes saw it, and who are willing to swear an oath that they have not added to nor falsified the above written.

Assuming the monks didn't make up the story, weren't tripping on fly agaric mushrooms, or having a prophetic vision of Space 1999; they obviously saw something extraordinary. But what the heck was it?

Occam's razor favors the "monks were lying" hypothesis. Proponents note that Gervase said the body of the moon was "below the horns", while in reality all crescent moons right after sunset have the body above the horns. But that's no fun.

A geologist named Jack Hartung figured the obvious hypothesis was that a freaking huge meteorite or comet impacted Luna and made all the fireworks. With something so spectacular, that's gotta leave a mark. So Hartung did a Lunar survey looking for suspiciously fresh craters.

Which leads us to Giordano Bruno crater.

The crater is on the northeast limb of the moon, which is consistent with Gervase's account. Jack Hartung did a lot of calculating to pinpoint the lunar latitude and longitude of the postulated impact, and Giordano Bruno is smack dab in the correct spot.

As for age, it is possible to date a crater by how bright its ray system is. The rays darken with age. Giordano Bruno is apparently the youngest crater of its size or larger on Luna. It is estimated to be less than 350 million years old. Perhaps even only 800 years old.

Giordano Bruno crater is 22 kilometers in diameter, which means the meteorite that created it was more like a small asteroid. Probably a rock from one to three kilometers in size, which is pretty huge. If it had struck Terra instead, it would have created an explosion firmly in the "civilization threatening" category. It was certainly capable of creating a fountain of molten Lunar lava big enough to freak out some monks.

Jack Hartung published his hypothesis in the September 1976 issue of the journal Meteoritic. In the article he goes over other possible explanations and points out their flaws.

Of course many other scientists tried to find flaws in Jack Hartung's hypothesis, because that is how science works. HH Nininger and Glenn I Huss came out a year later suggesting that the Giordano Bruno would have been almost invisible to the monks, especially since it is slightly on Luna's far side. They were in favor of the "atmospheric meteor heading right between the eyes of the monks" hypothesis. In other words a bolide close to the monks and far far away from Luna, but coincidentally in the monk-Luna line of sight. This would also explain why apparently nobody else on Terra saw it happen.

However Hartung's hypothesis was accepted for years because it is just so darn exciting.

A more serious objection was raised by graduate student Paul Withers in 2001. He did a bit of calculation and noted the impact would have ejected about ten million tons of Lunar debris. Further calculation revealed that enough would have hit Terra to make a week-long blizzard-like meteor storm on Earth with about 50,000 meteors per hour. Pretty much everybody on the planet would have seen it. The fact that there is zero mention of this in all of 12th century writing means either [a] a global conspiracy of silence or [b] it didn't happen.

The sad fact of the matter is that we cannot really know what the monks saw, and probably never will. But for a science fiction writer, this juicy bit of weird astronomical lore contains all sorts of possibilities for their next novel.

Planet Vulcan

No, this isn't the planet Mr. Spock comes from (that's around 40 Eridani A).

Back in 1781 famous astronomer William Herschel discovered the planet Uranus. Herschel wanted to name it Georgium Sidus (George's Star) after his patron King George III, but cooler heads prevailed.

Uranus has a year of about 84 Terran years long. So by 1847 astronomers had observation over almost a full Uranian year. Unfortunately the observed orbit did not agree with an orbit calculated by Newton's law of gravitation. Even if you took into account all the other known planets.

Quite a few scientists realized that while a flaw in Newton's law of gravity was not realistically possible, the discrepancy could be explained by the existence of an unknown planet. A few astronomers started to look into this, some encouraged by their physicists friends.

They worked backwards, trying to figure where the unknown planet had to be in order to have caused the perturbations. Urbain Le Verrier of France and John Couch Adams of England calculated the answer in a virtual photo finish. Le Verrier won by about two days, though England bitterly complained about it for years afterwards.

The planet Neptune was spotted on 23 September 1846, about 1° of where Le Verrier calculated it to be. Which is pretty much a bulls-eye.

Of course astronomers with dreams of fame had the idea of using the technique as a short-cut to planetary discovery and their name in the history books. Alas it never seemed to quite work out

Astronomer Percival Lowell was the person we can thank for all the science fiction stories featuring the "Canals of Mars."

Italian astronomer Giovanni Schiaparelli thought he saw straight lines on Mars during the great opposition of 1877. He was wrong, but he popularized them. Alas he described them using the Italian word canali, which means "ordinary garden variety channel or river." Lowell read this and translated the Italian canali into canal, which means "artificial waterway dug by the desperate Martian civilization living on a dying planet." This inspired such novels as Well's The War of the Worlds, Garrett P. Serviss' Edison's Conquest of Mars, Edgar Rice Burroughs' A Princess of Mars, and a host of others. Which is why everybody was so disappointed when Mariner 4 only saw a bunch of craters.

Anyway, Lowell noticed that the orbits of Uranus and Neptune were still not quite as predicted. Aha! It must be an undiscovered planet! Lowell started feverishly searching for "Planet X." Lowell died without finding anything, but the job was handed to a 22 year old astronomer-farmboy named Clyde Tombaugh. He discovered Pluto in 1930, but disappointingly Pluto was not Planet X. It had nowhere near enough mass. Later it was discovered that the discrepancies in the orbits of Uranus and Neptune were because astronomers had over-estimated the mass of Neptune. Planet X was a myth.

Finally getting to the point of this entry, Urbain Le Verrier, flush with the fame of Neptune, noticed discrepancies in the orbit of Mercury. Aha! It must be an undiscovered planet! Le Verrier called it "Vulcan" because the blacksmith of the Gods needed Sol as a furnace.

When Le Verrier talks, people listen. Especially if they are astronomers. Lots of astronomers made their eyes water, frantically examining the region around Sol hoping to be the first to spot Vulcan. Disappointingly, though many people thought they saw it, no body could spot it twice. Much less the three observations needed to calculate the orbit.

After Le Verrier died in 1877 people gave up looking.

In 1915 Einstein's General theory of Relativity gave the answer to the anomalous orbit of Mercury. It was not due to an undiscovered planet, but instead because of how space is warped by the intense gravity of Sol. This was very important in proving the validity of Relativity.

Some astronomers are of the opinion that a few of the "sightings" of Vulcan were due to a swarm of tiny asteroids near Sol, the so-called "vulcanoids." This is only of academic interest, since nobody cares about discovering a new dime-a-dozen asteroid. Not unless it is going to destroy Terra or do something else interesting. Though they may be nifty places to locate solar-powered antimatter factories or something.

Recently, some researchers noticed an unusual orbital configuration of a group of trans-Neptunian objects, and used an argument based on Newton's law of Gravitation to postulate a Planet Nine. Other researchers are of the opinion that the first group should learn a lesson from the sad tale of Planet Vulcan.

Solar Eclipse

A solar eclipse is an awesome astronomical event. The historical record is full of people being stunned and shocked by eclipses, doing things like halting battles in progress. Historians love this, since it allows them to date any event that happened close to an eclipse down to the second.

There is Sol, blazing away in broad daylight, and suddenly Luna moves over it, until it perfectly covers it.

Perfectly ... covers ... it.

Waitaminute. Sol is something like 700,000 kilometers in radius, how the heck can Luna cover it? Sol is 400 times larger that Luna.

Ah, but Luna is about 400 times closer to Terra than Sol is, that makes it work.

Ummm .... waitaminute. Sol is x400 the size of Luna, and Luna just happens to be exactly x400 closer? Isn't that rather ... unlikely?

And just to make it weirder, Luna's orbit is steadily widening. It is moving further away from Terra at the rate of about 3.5 cm per year. Which means that Luna only fits more-or-less perfectly over Sol during 0.00006% of Terra's entire lifespan, and mankind just happens to be living during it.

A clever science fiction author could find all sorts of entertaining ways to use this. The obvious conclusion is that Luna did not randomly arrive at its current position. Somebody moved it there.


      So lets think about eclipses for a moment. Even if we haven't seen an eclipse personally, we've seen phoptographs in magazines or the footage on television or youtube. We are almost blasé about them; they are just stuff that happens on our planet, like weather or earthquakes only not destructive, not life threatening.

     But think about it. What an incredible coincidence it is that our moon fits exactly over our sun. Talk to astronomers and they'll tell you that Earth's moon is relatively much bigger than any other moon around any other planet. Most planets, like Jupiter or Saturn and so on, have moons that are tiny in comparison to themselves. Earth's moon is enormous, and very close to us. If it was smaller or further away you'd only ever get partial eclipses; bigger or closer and would hide the sun completely and there'd be no halo of light round the moon in totality. This is an astounding coincidence, an incredible piece of luck. And for all we know, eclipses like this are unique. This could be a phenomenon that happens on Earth and nowhere else. So hold that thought eh?

     Now supposing there are aliens. Not E.T. aliens — not that cute or alone. Not Independence Day aliens — not that crazily aggressive — but, well, regular aliens. Yeah?…

     But what I want to propose to you is that, as well as all those other wonders, they want to see that one precious thing that we have and probably no one else does. They'd want to see our eclipse. They'd want to look through the Earth's atmosphere with their own eyes and see the moon fit over the sun, watch the light fade down to almost nothing, listen to the animals nearby fall silent and feel with their own skins the sudden chill in the air that comes with totality…

     …So that's where you look for aliens. In the course of an eclipse totality track.

From TRANSITION by Iain Banks (2009)

Lagrangian Points

Lagrangian Points are orbital positions of peculiar stability that are formed with respect to two given planets, moons, suns, or any combination of the two. In other words, if you put a satellite or space colony in a Lagrangian point, it will tend to stay there. This lets you save on propellant for your attitude jets.

Points L1, L2, and L3 are only partially stable. That is, if you are exactly on the point you will stay there, but if you are nudged off point you will rapidly be flung away (it is possible to "orbit" these points instead of perching on them). L4 and L5 are much more desirable. If you are nudged off-point, you will tend to fall back into the stable position.

Please keep in mind that the L4 and L5 points are on an equilateral triangle. This means that since the distance between Terra and Luna is about 400,000 kilometers, this is the same distance as between the Terra-Luna L5 point and Terra, and between that L5 point and Luna.

You've probably encountered Lagrangian points in reference to Dr Gerard K. O'Neill's L5 orbital colonies. If your colony is a thirty kilometer long cylinder, you don't want it crashing into Luna or something.

In the orbit of Jupiter, the Jupiter-Sol L4 and L5 points are occupied by the Trojan Asteroids. There are other such clusters in the orbits of all other planets in the solar system, but they have nowhere near as many objects as the Trojans. This is due to the size of Jupiter and its proximity to the asteroid belt.

In Larry Niven's novel PROTECTOR, Jack Brennan discovers a valuable collectible piece of space history (a spent solid fuel rocket from Mariner XX) in Uranus's trailing Trojan point. Others have suggested that various Trojan points should be investigated to find hypothetical ancient alien artifacts. The theory is that since things tend to collect in Trojan points, it is worth examining such points to see if any anomalous objects are there. Duncan Lunan has a theory that an alien space probe from Epsilon Boötis is loitering in the Terra-Luna L5 point, but nobody takes him seriously.

Home, home on Lagrange,
Where the space debris always collects,
We possess, so it seems, two of Man's greatest dreams:
Solar power and zero-gee sex.

HOME ON LAGRANGE (THE L5 SONG) by William S. Higgins and Barry D. Gehm (1977)

Solar Neutrino Problem

Neutrino are exotic subatomic particles whose existence was deduced when physicists noticed that the subatomic event called beta decay didn't add up. Mother Nature always balances her books, the law of conservation of mass-energy forces that.

(Well, technically the Uncertainty principle allows one to embezzle mass-energy as long as you pay it back in the few nanoseconds before the cosmic accountant checks the ledger. But I digress.)

So with all nuclear reactions, the sum of all the starting particles mass-energy before the reaction must be exactly equal to the sum after. The problem with beta decay is that they weren't.

In 1930 physicist Wolfgang Pauli said "I've got it! What if beta decay produces some as-yet undiscovered weird invisible particle with properties that will exactly balance the books? We just thought things were not balancing because we couldn't see the blasted thing."

The other physicists rolled their eyes at Pauli. This sounded too much like your infant son telling you that he didn't break the lamp, it was an invisible green monster trying to frame him. Violates Occam's razor, that does.

Twenty-six years later Pauli was vindicated when Clyde Cowan and Frederick Reines finally managed to detect the weird invisible particle.

Why did it take them so long? Because neutrinos are real invisible. The slippery little devils can pass through about one entire light-year of solid lead before it hits a lead nucleus. They are beyond elusive, but can be detected by a sufficiently sensitive detector. These are typically 1,000 metric tons of ultra-pure water in a tank coated with photocells buried deep underground in an abandoned mine.

Since neutrinos are so darn penetrating, they can be used to observe astronomical objects. In 1987 a couple of neutrino detectors accidentally spotted a few from Supernova 1987A. The neutrinos arrived about two hours before the visible light of the supernova. This is because the neutrinos were created by the initial stellar core collapse, while the light was not created until two hours later when the shock-wave reached the star's surface. The important point is that neutrinos can be used to observe conditions inside the cores of stars.

Which leads to this Weird Astronomical.

In 1970 astrophysicists Raymond Davis, Jr. and John N. Bahcall figured they could use a neutrino detector to measure the rate of nuclear fusion in our primary star Sol. The Sun in our sky that gives us daylight. A single photon of light created by a fusion reaction in the core of Sol can take between 100,000 years and 50 million years to gradually work its way to the surface of Sol, then 8 minutes more to travel to Terra. But the slippery neutrino acts like the body of Sol ain't there. It takes a mere 2.3 seconds to reach the surface of Sol, and 8 minutes more to reach Terra.

This will allow a much more current report on the state of affairs at Sol's core. 2.3 seconds instead of 50 million years.

So Davis and Bahcall set up a 100,000 gallon tank of perchloroethylene 1,478 meters underground in the Homestake Gold Mine in Lead, South Dakota.

Bahcall had done the theoretical calculations on how many solar neutrinos would reach the detector. Davis used the detector to count the number of neutrinos that actually arrived. That's when all the fun started.

The trouble was that the actual number of neutrinos detected was consistently about one-third the number predicted by Bahcall's calculations. Now, keep in mind that such trouble in Science is actually a good thing. Isaac Asimov noted "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' (I found it!) but 'That's funny ...'"

Properly following the dictates of the scientific method, the scientific community immediately declared that either Davis, Bahcall, or both had made a mistake. Both Davis and Bahcall double checked their work, but could find no errors.

The next step in the scientific method is for others to try and recreate the experiment and recreate the experimental results. Kamiokande in Japan, SAGE in the former Soviet Union, GALLEX in Italy, Super Kamiokande, also in Japan, and SNO (Sudbury Neutrino Observatory) in Ontario, Canada all tried it. Lo and behold, they got the same results. There were only one-third of the predicted amount of neutrinos coming out of Sol.

When you ask the question Why? is when things started getting edgy.

The two possibilities are: neutrinos are not understood as well as they thought or Sol is not understood as well as they thought. Or both.

The nuclear physicists shrugged, and promised to take a closer look and neutrino theory to see if there was anything they'd overlooked. If they found anything, particle physics would be updated with the new information. No big deal, science marches on and all that.

The solar astronomers started to sweat. The experimental results could mean that the rate of solar thermonuclear fusion had been drastically decreased by two-thirds. Which means the energy Terra receives from Sol could suddenly drop by two-thirds, at any moment from 50 million years in the future to eight minutes from now. The decrease would not be immediately apparent due to the 50 million year time lag of solar photons escaping the body of Sol. In that case the only question is how many millions of years in the past did the fusion rate stop?

Of course when the solar energy drops by two-thirds, Terra will die. Colder than a sno-cone in Niflheim.

Sir Arthur C. Clarke used this nifty situation as the background for his 1986 novel The Songs of Distant Earth. And there were a few popularization of science articles published with arresting titles along the lines of SCIENTISTS ARE UNSURE IF THE SUN WILL RISE TOMORROW.

The situation was resolved 2001 when the results came in from the Sudbury Neutrino Observatory (SNO) in Canada, to the relief of astronomers and the dismay of science fiction authors.

Since way back in the 1970's the Standard Model of particle physics predicted that there were three kinds of neutrinos, ordinary garden-variety electron neutrinos plus the exotic muon neutrinos and tau neutrinos. Solar fusion produced electron neutrinos but none of the other two.

Clever readers will have already noticed the coincidence between the number of different neutrinos being three, and the neutrino detectors finding only one third of the expected number of solar neutrinos.

Back in 1957 Bruno Pontecorvo proposed the theory of Neutrino oscillation. It predicted that a neutrino of one type could spontaneously transmute into another type, then another type as it shot through space. This was an interesting conjecture, but it was not for decades that physicists could figure out an experiment which could detect this.

Finally several experiments did. Ironically one of them was was the data from the previously mentioned Sudbury Neutrino Observatory looking for solar neutrinos. As it turns out, most of the other neutrino telescopes could only detect electron neutrinos but not the other two kinds.

The Super-Kamiokande collaboration in Japan produced evidence strongly suggesting that it was seeing cosmic-ray created muon neutrinos transmuting into tau neutrinos.

But the SNO used heavy water as the detection medium. This allowed it to detect all three types of neutrinos. It could not distinguish between muon neutrinos and tau neutrinos, but it could see both. But it could distinguish between electron neutrinos and the other two. In 2001 it showed that 35% of the arriving solar neutrinos are electron neutrinos, with the others being muon- or tau-neutrinos (invisible to most neutrino detectors). Notice that 35% is quite close to one-third. If the muon- and tau-neutrinos represented solar fusion electron neutrinos that had transmuted, then the rate of solar fusion was as predicted, and all's well with the world. Sol is not going to unexpectedly go ppssssst!, turn dark, and condemn the world to an arctic death.

Alas, yet another thrilling science-fictional idea first offered by Science but then snatched away.


     More than a thousand years later, a great historian had called the period 1901-2000 ‘the Century when everything happened’. He added that the people of the time would have agreed with him —but for entirely the wrong reasons.
     They would have pointed, often with justified pride, to the era’s scientific achievements — the conquest of the air, the release of atomic energy, the discovery of the basic principles of life, the electronics and communications revolution, the beginnings of artificial intelligence — and most spectacular of all, the exploration of the solar system and the first landing on the Moon. But as the historian pointed out, with the 20/20 accuracy of hindsight, not one in a thousand would even have heard of the discovery that transcended all these events by threatening to make them utterly irrelevant.
     It seemed as harmless, and as far from human affairs, as the fogged photographic plate in Becquerel’s laboratory that led, in only fifty years, to the fireball above Hiroshima. Indeed, it was a by-product of that same research, and began in equal innocence.
     Nature is a very strict accountant, and always balances her books. So physicists were extremely puzzled when they discovered certain nuclear reactions in which, after all the fragments were added up, something seemed to be missing on one side of the equation.
     Like a bookkeeper hastily replenishing the petty cash to keep one jump ahead of the auditors, the physicists were forced to invent a new particle. And, to account for the discrepancy, it had to be a most peculiar one — with neither mass nor charge, and so fantastically penetrating that it could pass, without noticeable inconvenience, through a wall of lead billions of kilometres thick.
     This phantom was given the nickname ‘neutrino’ — neutron plus bambino. There seemed no hope of ever detecting so elusive an entity; but in 1956, by heroic feats of instrumentation, the physicists had caught the first few specimens. It was also a triumph for the theoreticians, who now found their unlikely equations verified.
     The world as a whole neither knew nor cared; but the countdown to doomsday had begun.

     No one heard the first tolling of Earth’s funeral bell — not even the scientists who made the fatal discovery, far underground, in an abandoned Colorado gold mine.
     It was a daring experiment, quite inconceivable before the mid-twentieth century. Once the neutrino had been detected, it was quickly realized that mankind had a new window on the universe. Something so penetrating that it passed through a planet as easily as light through a sheet of glass could be used to look into the hearts of suns.
     Especially the Sun. Astronomers were confident that they understood the reactions powering the solar furnace, upon which all life on Earth ultimately depended. At the enormous pressures and temperatures at the Sun’s core, hydrogen was fused to helium, in a series of reactions that liberated vast amounts of energy. And, as an incidental by-product, neutrinos.
     Finding the trillions of tons of matter in their way no more obstacle than a wisp of smoke, those solar neutrinos raced up from their birthplace at the velocity of light. Just two seconds later they emerged into space, and spread outward across the universe. However many stars and planets they encountered, most of them would still have evaded capture by the insubstantial ghost of ‘solid’ matter when Time itself came to an end.
     Eight minutes after they had left the Sun, a tiny fraction of the solar torrent swept through the Earth — and an even smaller fraction was intercepted by the scientists in Colorado. They had buried their equipment more than a kilometre underground so that all the less penetrating radiations would be filtered out and they could trap the rare, genuine messengers from the heart of the Sun. By counting the captured neutrinos, they hoped to study in detail conditions at a spot that, as any philosopher could easily prove, was forever barred from human knowledge or observation.
     The experiment worked; solar neutrinos were detected. But —there were far too few of them. There should have been three or four times as many as the massive instrumentation had succeeded in capturing.
     Clearly, something was wrong, and during the 1970s the Case of the Missing Neutrinos escalated to a major scientific scandal. Equipment was checked and rechecked, theories were overhauled, and the experiment rerun scores of times — always with the same baffling result.
     By the end of the twentieth century, the astrophysicists had been forced to accept a disturbing conclusion — though as yet, no one realized its full implications.
     There was nothing wrong with the theory, or with the equipment. The trouble lay inside the Sun.
     The first secret meeting in the history of the International Astronomical Union took place in 2008 at Aspen, Colorado — not far from the scene of the original experiment, which had now been repeated in a dozen countries. A week later IAU Special Bulletin No. 55/08, bearing the deliberately low-key title ‘Some Notes on Solar Reactions’, was in the hands of every government on Earth.

(ed note: the novel was written in 1986, then the year 2008 was two decades in the future)

     One might have thought that as the news slowly leaked out, the announcement of the End of the World would have produced a certain amount of panic. In fact, the general reaction was a stunned silence — then a shrug of the shoulders and the resumption of normal, everyday business.
     Few governments had ever looked more than an election ahead, few individuals beyond the lifetimes of their grandchildren. And anyway, the astronomers might be wrong. Even if humanity was under sentence of death, the date of execution was still indefinite. The Sun would not blow up for at least a thousand years, and who could weep for the fortieth generation?

From THE SONGS OF DISTANT EARTH by Arthur C. Clarke (1986)

Maunder Minimum

Sunspots are spots, on the Sun. They look like dark dots but they are only relatively dark. They are shining at about 4,200 °C (bright enough to blind you), it is just that the rest of the Sun is shining at 5,500 °C. So the spots are dark in comparison.

While they had been reported by Chinese astronomers thousands of years ago (there was a reference in the Book of Changes, c. 800 BC), the parochial self-centered powers that be in Europe could easily ignore reports of inconvenient truths from those heathen foreigners in distant lands. What had those blasted Chinese invented anyway that was worth anything? Well, besides paper, printing, gunpowder, the magnetic compass, and hundreds of others...

Unfortunately it was not quite so easy for the European PTB to ignore trouble-makers like Galileo, who had the audacity to invent scientific instruments that blatantly revealed the existence of things that the Church insisted did not exist. Like sunspots. A few other European scientists had seen and written about sunspots before Galileo did in the 1600s, but Galileo had a better PR department. Which meant it was Galileo who was brought up on charges before the Inquisition and threatened with an assortment of unspeakable tortures for doing stupid things like making the Church look like fools on subjects like the orbit of comets, spots on the Sun, and heliocentrism. Trifle with the infallibility of the Church at your own peril, fool.

European scientists still studied sunspots, but now they kept their mouths shut. Over the decades the records of scientific observations of sunspots gradually grew.

About two hundred years later in the late 1800s German Astronomer Gustav Spörer noticed something odd about the sunspot records. He wrote a paper about his findings in 1887. The British husband and wife team of astronomers Edward Maunder and Annie Maunder studied Spörer work and popularized it in a couple of papers of their own. Though criminally Annie Maunder's contributions were not recognized because being a male chauvinist pig was sadly widespread at the time (and shamefully still exists in the current day). For their work the phenomenon was named after the Maunders, which annoyed the Germans.

In the 1970s US astronomer John Eddy studied Spörer and the Maunder's work, and wrote a little paper about it. The paper wound up as the cover article in the June 1976 issue of Science magazine, and became a smash hit. John Eddy became famous, though he did have the kindness to popularize the effect under the Maunder's name instead of his own.

What is this effect? Why, the Maunder Minimum of course.

The sunspot records showed that the average number of sunspot rises and falls on a fairly regular 11 year cycle. Interesting but not earth-shattering.

Except for that disturbing 70 year gap from 1645 to 1715. Where there were no sunspots. At all.

And this was not just a gap in observations, there are records of the astronomers of the time pulling their hair out trying to figure out where all the blasted sunspots had gone..

This was only somewhat disturbing. The really awfully terrifyingly disturbing part is that the Maunder Minimum more or less corresponds to a particularly cold section in the middle part of the freaking Little Ice Age.

John Eddy identified another spotless period, 90 years from 1460 until 1550. He discovered it by analyzing carbon-14 in tree rings, since this pre-dated European astronomers keeping sunspot records. In a nice gesture he named it the Spörer Minimum. This period also corresponds to a particularly cold stretch of the Little Ice Age.

Other astronomers discovered the Dalton Minimum, lasting from 1796 to 1820 and also corresponding to a frigid part of the Little Ice Age.

Scientist are still bitterly divided over the connection, if any. There does not seem to be any direct mechanism between the number of sunspots and global temperatures. Occam's Razor suggests that the sunspots must affect solar output, but other scientists think it is just a coincidence or spotty data (which seems a little unlikely).

As a science fiction writer, the question becomes when will the next minimum occur, and what will happen then?


Back around 400 BCE the Greek philosopher Philolaus was not too happy with geocentric cosmology but arguably his non-geocentric cosmology was not much of an improvement. By the raw power of deduction he postulated the existence of a couple of astronomical bodies that conveniently could not be seen. One was the "central fire" (not the sun, it revolved around the central fire with all the other planets) and the other was Ἀντίχθων (Antichthon) or "Counter-Earth."

Philolaus fell into the dust-bin of history, but Counter-Earth just wouldn't die. It was seen as a planet the same size as Terra, in Terra's exact orbit, but exactly on the opposite side. Which means you can't see it because the Sun is always in the way. Since it was the same size and in the same ecosphere, it could be just as habitable and full of life as Terra.

How romantic was that! Counter-Earth became a favorite of pulp science fiction authors, comic book writers, and UFO true believers.

The 32 infamous Gor novels were set on Counter-Earth. The 1969 science-fiction film Doppelgänger (aka Journey to the Far Side of the Sun) features an expedition to Counter-Earth. Several series of Marvel Comics are set on Counter-Earth, which had been created by the High Evolutionary. And of course it was the obvious place for flying saucer aliens to hide.

It is a real shame Counter-Earth doesn't exist.

Counter-Earth would be in the Terra-Sol Lagrange 3 point, which is nowhere near stable. The gravity of other planets would induce Counter-Earth to migrate to the L4 or L5 point, in clear view of Terran telescopes. Astronomers would have known about Counter-Earth for decades even if it wasn't visible, due to the effect of Counter-Earth's gravity on the other planets and space probes. And speaking of space probes, quite a few have turned their cameras on the location of Counter-Earth, and there ain't nuttin' there.

Another cherished legend bites the dust.

In Arthur C. Clarke's short story Love That Universe, Antigean Station is a space station established at Terra-Sol Lagrange 3 point. This is for research which needs shielding from the interference from Terra, since the sun is blocking the way. The story then veers off in a science-fantasy direction, since they discover the laws of psionics. This is because the background roar of a billion minds makes it impossible to measure psi signals on Terra. Sort of like trying to discover the laws of music in a boiler factory.

Deimosian Ice

As mentioned above, with respect to space industrialization and colonization, water ice is one of the most valuable things in the universe. You don't want to haul it up Terra's horrific gravity well, you can get it for much less delta V cost from the Lunar poles.

However, there is another source with an even lower delta V cost: the Martian moon Deimos. Yes, the trip time is larger by about two orders of magnitude, but an entire kilometer per second of delta V savings is nothing to sneeze at.

Rob Davidoff and I worked up a science fiction background where the Martian moon Deimos becomes the water supplier for the entire solar system in our Cape Dread.

delta-V for Transfers from LEO
Locale to LEOLEO to Locale
Localedelta-VTrip Timedelta-VTrip Time
Lunar Base6.2 km/s3 days3.2 km/s3 days
Deimos5.6 km/s270 days1.8 km/s270 days

Better still, although the origins of both Deimos and Phobos are yet unsettled, both appear to have the characteristics of dark carbonaceous asteroids, with anhydrous silicates, carbon, organic compounds, and ice (Bell et al. 1992). If this bears out, Deimos’ regolith would be able to provide water and other volatiles for life support and propellant. Besides silicates, its regolith will also likely contain metals and other valuable materials for construction and manufacturing (Norton 2002).

In this plan, I find it hard to see any good in wasting money and time on the Moon step. Deimos requires less delta-v to get to/from anyway. If it can be exploited for oxygen propellant, then it would be a better place to get it than the Moon (which has a rather steep gravity well).

Also, while I'm generally wary of tether schemes, I must admit that they might be useful for transferring stuff from Deimos to Earth. Deimos starts off in a somewhat inconvenient circular orbit. One or more rotating tethers made out of "waste" metal from oxygen extraction could be used to sling payloads into an elliptical orbit more suitable for navigation back to Earth.

That said, I really think it's better to get oxygen from Earth's atmosphere or maybe Venus or Mars. Much simpler processing, and uses mostly off the shelf satellite technology.

Isaac Kuo

Grooves of Phobos

When NASA's Viking orbiter 1 space probe got close enough to the Martian moon Phobos to get halfway decent photographs, scientists were nonplussed to discover it had lots of parallel grooves all over it. They then spent the next forty years trying to formulate a theory explaining this bizarre marking that would hold water for five minutes.

First they figured these were stress fractures from the titanic impact which formed the huge Stickney crater. After all, the freaking crater is a whopping 9 km in diameter, Phobos itself is only 22.6 km in mean diameter. You'd expect lots of crack from that collision.

Unfortunately for that theory, the Mars Express space probe discovered the grooves were totally unrelated to Stickney. Instead of radiating from Stickney, the grooves were more or less aligned with the moon's orbit.

The next theory noted that Phobos' orbit is spiraling in closer to Mars. It is approaching the Roche limit, where the earth tides created by the Martian gravity will shred the moon and turn it into a planetary ring. Scientist calculate that Phobos will die in a mere 30–50 million years.

So the theory was that the grooves were "stretch marks" created as the Martian gravity gradually pulled the moon apart.

Unfortunately for that theory, when the tidal forces were calculated they proved to be far to weak to create such stretch marks in a solid moon the size of Phobos.

The next theory was that maybe Phobos was not a solid moon, but more a flying pile of rubble and gravel (a Mohr–Coulomb body). For this to work Phobos would have to be a a rubble pile surrounded by a 100 m layer of regolith.

Unfortunately for that theory, other scientist pointed out that some of the grooves are not grooves so much as they are chains of craters. Which are not formed by tidal forces.

The next theory was that the craters were formed by a separate process from the grooves, specifically by Phobos being machine-gunned by shrapnel coming from Mars, rising from the explosive birth of a new Martian meteorite crater. Since Phobos would be traveling cross-wise through the shrapnel plume, this would create a chain of craters. Much like a perfect row of bullet holes punched into a railroad train when somebody fires a machine gun perpendicular to the train tracks.

Unfortunately for that theory, other scientist pointed out that there were "zones of avoidance" on Phobos, where there were no chains of craters. Plumes of shrapnel from Mars would have laid crater chains all over the zones of avoidance.

The most recent theory is from M. Nayak and E. Asphaug.

In the past, theorists had considered and rejected the idea that the crater chains were formed by shrapnel from newly formed meteorite impacts on Phobos. The trouble with that idea are twofold: [a] such crater chains would be radial, not parallel and [b] the observed crater chains do not seem to originate with any large Phobosian mother crater.

Nayak and Asphaug reasoned that the chains could not be formed from new-crater shrapnel that did not exceed Phobos' escape velocity (that is, the shrapnel rises from the crater and immediately falls down to hit Phobos), for the two reasons mentioned above.

And obviously the chains could not be formed from new-crater shrapnel that exceeded the Martian escape velocity. They would go flying off into the black depths of the solar system.

But Nayak and Asphaug said waitaminute, there is a third option everybody was overlooking.

What about shrapnel that exceeds Phobos' escape velocity but not the Martian escape velocity?

This shrapnel would go into orbit around Mars. Tidal forces will tend to clump the shrapnel. So when Phobos plows into one of these clumps, the result will be parallel chains of craters.

Stay tuned to see if this theory survives.

Asteroid Belt

Everybody knows that the Asteroid belt is a bunch of huge rocks orbiting between Mars and Jupiter. This is true.

Everybody also knows that inside the belt it looks like Han Solo being chased by TIE fighters in the movie The Empire Strikes back. This is wrong. The average separation between asteroids is sixteen times the distance between Terra and Luna. If you were standing on a random asteroid, chances are you would not be able to see any other asteroids. Not without a telescope and an ephemeris.

TV Tropes calls the fallacy of Empire Strikes Back jam-packed belts the "Asteroid Thicket".

In 1802, hypnotised by the seductive symmetry of the (now discredited) Titius-Bode Law, astronomer Heinrich Olbers suggested that the asteroid belt was the remains of a an exploded planet (usually called Phaeton, Phaethon or Phaëton). Science fiction authors of the 1940's and 50's used this idea quite a bit, since it is incredibly awesome and cosmic. In many of those scifi stories the planet was blown into asteroid smithereens by an atomic war waged by the inhabitants, in others it is due to some naturally occurring astronomical catastrophe, or a scientific experiment gone wrong. You can find a list of exploding Phaëton stories here.

This is now commonly thought by astronomers to be false:

  • The amount of energy required to explode and spread a planet around the belt would be, er, ah, astronomical.
  • If you gathered all the asteroids together into one planet, the pathetic thing would be about 4% the size of Luna (3.2×1021 kg).
  • The chemical composition of asteroids differ so wildly that it is difficult to explain how they come from the same planet.

Nowadays astronomers think the belt represents where Jupiter's gravity prevented a planet from being born.

There are 200 known asteroids with a diameter larger than 100 kilometers. There are approximately 0.7 to 1.7 million asteroids with a diameter larger than 1 kilometer.

The total mass of the asteroid belt is about 3.2×1021 kg. One-third of this is the asteroid Ceres. One-half of this is the combination of Ceres, Vesta, Pallas, and Hygiea.

16 Psyche

Asteroid 16 Psyche is a weird one.

When it comes to the top most-massive asteroids, Psyche is right there at number 11. Blasted thing contains about 1% of the mass of the entire freaking asteroid belt, about (2.72±0.75)×1019 kilograms. But that's not the weird part.

That space rock is no rock, it is almost 100% solid nickel-iron. Actually, Chris Wolfe estimates it is about five parts per million platinum group metals, which is about 110 billion tons of PGM.

As a general rule, asteroids are not composed of just one substance like that. They are composed of many substances that are either [A] blended into a homogeneous mass or [b] large and hot enough to differentiate into layers of pure substances like an asteroidal rainbow gobstopper candy.

So how did Psyche get like that? The main theory is that it was once a cosmic rainbow gobstopper, but it got the snot beat out of it by multiple hit-and-run collisions with proto-planets. These collisions peeled off the outer rainbow layers, leaving only the nickel-iron core. The outer layers should be still nearby, but astronomers cannot find them. Perhaps they were long ago pounded into dust.

I'm sure a hypothetical deep space steel mill megacorporation in a hypothetical asteroid civilization will find Psyche to be the undisputed mother-load. And if there are more than one deep space steel mill megacorporation they will indisputably find Psyche worth fighting several wars over.

The core could have cooled off from the outside in or cooled off from the inside out. If the latter, Psyche could also be a titanic magnet. I'm sure evil science fiction authors can think of all sorts of diabolical plot complications using that little fact.

Before the Iron Age mankind did not have the technology to smelt iron from iron oxide ore. The only source of unoxidized metallic iron was from enstatite chondrite meteorites aka "thunderbolt iron". Telluric iron doesn't really count since it is only found in one deposit in the isolated island of Greenland.

If you lived in the Bronze age, you knew your brittle bronze sword was no match for a hero wielding a legendary sword forged out of metal from a star. True, a meteoric iron sword is inferior to a modern-day steel sword, but against a bronze sword it might as well be made out of adamantium. Some researchers wonder if the advent of meteoric iron weapons gave rise to the myth of supernatural creatures only being vulnerable to "cold iron", but I digress.

As it turns out, most enstatite chondrites have been been spectrographically traced to have originated from 16 Psyche, planetoid of the meteor swords.

Some early science fiction stories (i.e., When Worlds Collide) postulated some mysterious mineral or element only found in the cores of planets and useful for something like super-duper armor or lining the reaction chambers of atomic engines. If this handwavium existed, 16 Psyche would be the logical place to mine the stuff.


Imagine a metal asteroid spewing molten iron, and you’ve got the gist of ferrovolcanism — a new type of planetary activity proposed recently by two research teams.

When NASA launches a probe to a metal asteroid called Psyche in 2022, planetary scientists will be able to search for signs of such volcanic activity in the object’s past. The new research “is the first time anyone has worked out what volcanism is likely to look like on these asteroids,” says planetary scientist Jacob Abrahams of the University of California, Santa Cruz.

Metal asteroids are thought to be the exposed iron-rich cores of planetesimals that suffered a catastrophic collision as the solar system was developing, before they could grow into full-sized planets. The naked core would have been exposed to cold space while still molten. And it would have cooled and solidified from the outside in, forming a solid iron crust that would be denser than the underlying molten iron, say Abrahams and planetary scientist Francis Nimmo, also of the University of California, Santa Cruz.

That kind of density mismatch is part of what can create volcanoes on Earth — lighter, more buoyant material rising up through cracks in the crust — and could have led to iron-spewing volcanoes on metal asteroids as the objects cooled long ago, the researchers speculate.

Another way that ferrovolcanism could have occurred on metal asteroids was described by planetary scientist Brandon Johnson of Brown University in Providence, R.I. If a cooling iron core also contained a little bit of rock and sulfur, he theorizes, the core could have been cocooned beneath a rocky, not iron, crust. As the core cooled further, pockets of iron-rich liquid with extra sulfur dissolved in them would have hardened more slowly than surrounding materials. Those pockets would be more buoyant than the rock above them, so they’d force their way up and out, Johnson says.

If Psyche has such a rocky veneer over iron, that could explain why the asteroid appears much less dense than expected, Johnson says. The two groups, which worked independently from one another, presented their ideas March 21 at the Lunar and Planetary Science Conference in The Woodlands, Texas.

“We kept thinking, ‘It’s too wild, it can’t be right,’ ” says Johnson, of the idea of ferrovolcanism. “But we couldn’t prove to ourselves that it wouldn’t work. Because another group came up with the same idea at the same time, it can’t be too wild.”

The Psyche spacecraft can look for signs of past ferrovolcanism when it arrives at the eponymous asteroid, located in the main asteroid belt between Mars and Jupiter, in 2026, says mission principal investigator and planetary scientist Lindy Elkins-Tanton.

What’s more, if Psyche were rotating while it cooled, its molten core could have generated a magnetic field. Volcanic flows that cooled on the asteroid’s surface would have recorded evidence of that magnetic field. “We might actually be able to see these things,” says Elkins-Tanton, of Arizona State University in Tempe. “I think it’s really cool.”

Asteroid P/2010 A2

P/2010 A2 was initially thought to be a comet, since it had a tail. But after closer examination, it was noted that the tail was not composed of cometary ices, it was actually rock dust. And unlike all comets, the nucleus was not in the center of the dust halo. It wasn't even on the axis of the tail.

P/2010 A2 is now thought to be an asteroid about 150 meters in diameter that was struck by a smaller asteroid about one meter in diameter. Or this is a snapshot of a Klingon battle cruiser whizzing through the asteroid belt: you decide.

P/2010 A2's orbit implies that it is a member of the Flora asteroid family. This family is probably the source of the K/T impactor that is thought to have killed off the dinosaurs.

Asteroid P/2012 F5

Researcher noticed that Asteroid P/2012 F5 had spat out four largish fragments, at suspiciously regular intervals. Then they noticed the blasted asteroid was spinning like a top (one rotation every 3.24 hours), easily fast enough to spontaneously break apart.

They had suspected this sort of thing happens, but this is the first time they caught it in the act. The two leading theories of why active asteroids emit fragments is either due to high spin rates or by collision with other asteroids. Asteroid P/2012 F5 is strong proof for the high spin rate theory.

The asteroid probably increase its spin rate due to the Yarkovsky effect, caused by uneven emission of thermal radiation. This generally only happens with asteroids smaller than 10 kilometers in diameter.



I’ve said it before, and I’ll say it again: There’s nothing like being there.

This isn’t just an aphorism; when it comes to asteroids it’s the literal truth. NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) spacecraft is making that incredibly clear. Astronomers had some idea of the asteroid Bennu’s size and shape from ground-based observations, but once the spacecraft got there, well, it was basically one surprise after another.

There’s a lot of cool stuff to describe, but the one thing that really shocked me — as well as the planetary science team in charge of the spacecraft data — is that Bennu is active. What I mean by that is that it’s spitting material out into space from its surface.

That … that is unexpected. To say the least.

The asteroid is shooting rocks into space. This isn’t like a comet, where ice gets heated up by sunlight and turns into a vapor, expanding away and taking debris like dust and pebbles with it*. Some process on Bennu is flicking out individual pieces of rock, one at a time or a few dozen at once. They range in size from a few to a few dozen centimeters across, which also shocked me. I figured they’d be like grains of sand, but these are big!

This was discovered by comparing images taken a few seconds apart. The particles are moving away from the surface, so they appear in different places in the two images. The spacecraft moves as well, so the background stars shift position, too, but always by the same amount, so they can be ignored.

They’ve only just begun studying these ejected bits, but from the analysis so far the scientists have been able to determine that the velocities of the particles range from a few centimeters per second up to 3 meters second (roughly jogging speed). While some of them fall back to the surface, some don’t. The escape velocity — how fast something must be ejected to leave and never come back — varies due to the asteroid’s weird double-cone shape, but it’s less than 1 kilometer per hour, so a lot of those ejected rocks ain’t coming back.

Amazingly, some of them are sent out right at the sweet spot in velocity, and actually go into orbit around the asteroid! However, these are highly elliptical orbits, bringing them back close to the surface. The irregular gravity of Bennu bends the orbit shape, so most if not all of these will wind up eventually coming back and falling onto the surface of Bennu anyway, probably after orbiting for a few days up to a month or two.

So what’s causing this phenomenon? Here’s the fun part: No one knows!

Seriously, this was unexpected and never seen before, so the scientists are scratching their heads. It may be due to something like ice just under the surface turning to gas and flinging stuff away, but that seems like a relatively low-pressure event, and even in the low gravity it takes some force to launch a rock 20 cm across to a distance of several hundred meters up.

I wonder if big rocks settling under strain can do it. The gravity is weak, but it’s there, and some of the rocks are pretty big. The asteroid’s spin adds a force outward, and that changes rapidly from the poles (where it’s weakest) to the equator (where it’s strongest), which causes odd forces across the surface. A big rock settling might be able produce enough force to ping a small rock or a chip into space. I’ll note that another group of scientists has determined that thermal stress — the repeated cooling and heating of rocks by the Sun as Bennu rotates — is causing the boulders to break down over time. It’s a slow process, but I wonder if that might be behind this. A boulder cracking is bound to launch shrapnel away.

The scientists are all over this, of course, and hopefully we’ll have some answers soon.

Another big result is that the surface is much rougher than expected. Radar observations taken from Earth (similar to the method cops use to track car speeds) indicated the surface was likely smooth, with rocks in the centimeter size range strewn across it.

That is most definitely not the case.

Yes, there are lots of small rocks, but the surface is covered with bigger ones, and they counted 200 rocks bigger than 10 meters in size, which was completely unexpected. The biggest is a huge 58 meters in size! That’s more than half the length of a football field.

It’s unclear why the surface is so rough. It also presents a problem. OSIRIS-REx is supposed to land on the surface of Bennu and grab a sample to bring back to Earth. They were looking for a clear space about 25 meters across to do this, and none that size exists! There are some small relatively smooth patches, but they’re a very tight fit for the spacecraft.

The scientists are looking at this very carefully to figure out what to do. The good news is that the biggest patch may be just enough to fit the spacecraft, and it looks like it contains regolith — finely ground-up particles of rock. That’s good, because the mission is designed to puff nitrogen gas onto the surface to blow the particles up and into a collection chamber.

The minerology of Bennu looks a lot like a certain class of rare meteorite that has been found on Earth, and we strongly suspect small asteroids like Bennu are their source. The sample return will provide a clean, unmodified piece of the asteroid for scientists to coo and cluck over in the lab, which should yield all sorts of fun results.

Some of the stuff they see on the surface are phyllosicates — clay — and iron oxide — rust. Those both form in the presence of water! There’s not a lot of water (in the form of ice) in Bennu that could make these. However, billons of years ago Bennu was part of a larger, parent asteroid that probably did have abundant water ice. If it got heated (perhaps through impacts), then the water could have mixed with other minerals to make the clay and rust. When an impact on that parent rock caused Bennu to be ejected and become an asteroid on its own, some of that material went with it.

One more thing. I’ve written before on how Bennu (and Ryugu, an asteroid currently being visited by the Japanese Hayabusa2 spacecraft) are rubble piles, basically collections of rocks held together by their own gravity. In other words, Bennu isn’t solid! It’s not some monolithic rock, but more like a bag of rocks. Now, as the spacecraft orbits Bennu it feels the asteroid’s gravity, which depends on its mass. The size has also been measured, which means the density can be calculated — and it’s only 1.19 grams per cubic centimeter!

I exclaimed out loud when I read that. That’s barely denser than water (which is 1 g/cc) and a lot less than solid rock, which is usually 2 – 3 g/cc. This means that Bennu is extremely porous, and may be more than 50% empty space.

Its interior may be big rocks just all jumbled together, with nothing in between them. Just voids. Wow. Small asteroids are weird.

This also seals Bennu’s fate. This has to do with a complicated process called the YORP effect — in a nutshell, sunlight warms the surface of the asteroid, which then radiates away that heat as infrared light, which in turn gives a small but measurable kick to the asteroid. This very slowly ramps up the asteroid’s spin, decreasing its rotation period by about one second every century. It’s a slow but inexorable effect, and eventually it will spin so rapidly that the centrifugal force outward will overcome the gravitational force inward … and at that point Bennu will fly itself apart.

That won’t be for millions of years, so we have plenty of time to keep studying Bennu. That’s good, because there’s a lot of weirdness to go around (I had to leave a lot of interesting things off because this article would be 5,000 words long if I included everything!), and it’ll definitely take scientists quite some time to understand this bizarre little world.

* On comets this tends to happen from open pits called vents, and the material sprays away in plumes. Too bad this doesn’t happen on the asteroid, because then I could have titled this post “Bennu and the Jets.”

Horseshoe Orbit Asteroid

Horseshoe orbits occur when something small (like an asteroid) is in almost the same orbit as something large (like Terra). The orbit is only horseshoe shaped when plotted relative to the large body and the Sun (in the "rotating reference frame"). But it still is weird.

Saturn's moons Epimetheus and Janus occupy horseshoe orbits with respect to each other, but the ones SF authors will be interested in are the asteroids that have horseshoe orbits with respect to Terra. These include 54509 YORP, 2002 AA29, and most recently 2010 SO16. 2010 SO16 is unusual because it is exceedingly stable compared to the others. According to simulations it will probably be stable for at least the next 120,000 years, and maybe for more than a million years.

From the view point of 2010 SO16, it travels in its orbit, and eventually sees Terra approaching from the front (in the direction of motion). Terra will come quite close, then Terra will seem to reverse course and start to recede into the distance. About 175 years later, 2010 SO16 will see Terra coming close in the rear view mirror. Again Terra will come quite close, then suddenly seem to reverse course and start to recede. 175 years later the cycle repeats. 2010 SO16 never gets closer to Terra than about 50 times the distance between Terra and Luna.

The details of how such an orbit is possible are explained here, here, and here.

From a science fiction author's viewpoint, you start with the absurdity of 2010 SO16 being so perfectly stable. Obviously some intelligent agency moved the asteroid into that orbit. Brainstorm the identity of the intelligence (secret super-scientific conspiracy, aliens, space creature disguised as an asteroid), the motive for the 175 year period, and you will be well on the way to having a nice background for your novel.

Primordial Asteroid Family

Southwest Research Institute was part of an international team studying the asteroid belt. They were identifying which asteroids were formed by collisions, and which were original members of the asteroid belt. They identified all the "families" of asteroids, that is, clusters that were originally a primordial asteroid which was fragmented in the belt demolition derby.

That's when the SwRI noticed a giant void in the main belt, populated by only a handfull of asteroids.

They concluded that these are primordial asteroids, relics left over from the birth of the solar system itself. Probably at least four billion years old.

Which might be interesting for any science fiction author looking for a place to site sleeping eldritch horrors from the dawn of creation, like Xul Hunters of the Dawn, protomolecules, and dreaming Cthulhus.

Ganymede's Enki Catena

Jupiter's large gravitational field is sort of a broom to sweep up comets. Some are deflected right out of the solar system. Ones that come too close enter the Roche Limit and are torn apart by tidal forces.

A long time ago such an unfortunate comet was fragmented. But before it could be flung away it collided with Ganymede. Since the fragments were still close together in line astern formation, they formed a chain of craters. As per the the International Astronomical Union's rules on planetary nomenclature, the official name for a crater chain is "catena" (plural catenae). This particular chain was named Enki after the principal water god of the Summerians. The full name is "Enki Catena"

Predictably for a moon of a comet broom, Enki Catena is not the only crater chain in the area. Ganymede has a total of four named catenae, Callisto has eight, and Io has three.

Saturn's Ring Spokes

The rings of Saturn occasionally exhibit ghostly radial spokes that seemingly defy the laws of gravity. They were first spotted by the Voyager 1 space probe in 1980. When the Cassini space probe arrived in 2004, the spokes were absent, but they turned up in 2005. There are many theories about the spokes, but nobody knows for sure. They are thought to be electrically charged sheets of dust-sized particles but their source is unknown. Some say they are caused by meteors impacting the rings. Others say that lightning bolts in Saturn's atmosphere created electron beams that rake the rings. They do seem to be a seasonal phenomenon, occurring around the Saturnian equinox.


But the glory of the rings continually drew Bowman’s eye away from the planet; in their complexity of detail, and delicacy of shading, they were a universe in themselves. In addition to the great main gap between the inner and outer rings, there were at least fifty other subdivisions or boundaries, where there were distinct changes in the brightness of the planet’s gigantic halo. It was as if Saturn was surrounded by scores of concentric hoops, all touching each other, all so flat that they might have been cut from the thinnest possible paper. The system of the rings looked like some delicate work of art, or a fragile toy to be admired but never touched. By no effort of the will could Bowman really appreciate its true scale, and convince himself that the whole planet Earth, if set down here, would look like a ball bearing rolling round the rim of a dinner plate.

Sometimes a star would drift behind the rings, losing only a little of its brilliancy as it did so. It would continue to shine through their translucent material — though often it would twinkle slightly as some larger fragment of orbiting debris eclipsed it.

For the rings, as had been known since the nineteenth century, were not solid: that was a mechanical impossibility. They consisted of countless myriads of fragments — perhaps the remains of a moon that had come too close and had been torn to pieces by the great planet’s tidal pull. Whatever their origin, the human race was fortunate to have seen such a wonder; it could exist for only a brief moment of time in the history of the Solar System.

As long ago as 1945, a British astronomer had pointed out that the rings were ephemeral; gravitational forces were at work which would soon destroy them. Taking this argument backward in time, it therefore followed that they had been created only recently — a mere two or three million years ago.

But no one had ever given the slightest thought to the curious coincidence that the rings of Saturn had been born at the same time as the human race.

From 2001 A SPACE ODYSSEY by Arthur C. Clarke (1968)

Saturn's Hexagon

Back in the early 1980's, the Voyager space probe sent back some pictures of Saturn that had astronomers rubbing their eyes to ensure they were seeing properly. Apparently Saturn's north pole was surrounded by a jet stream in the shape of a hexagon. The Cassini space probe went by Saturn in 2007, and yes, the hexagon was still there. Apparently this was not a short-lived phenomenon (or the blasted hexagon can be turned off then on again). Scientists were annoyed, since hexagons are generally constructed by living creatures (like humans or bees) but you'd expect lots of different visible signs of native Saturnians besides a solitary hexagon. Granted there are some naturally occurring hexagonal crystals, but this thing on Saturn was composed of gas and was twice as wide as Terra.

But scientist were spared the necessity of postulating the existence of powerful space aliens turning Saturn into a titanic wargaming hex map by physicists Ana Claudia Barbosa Aguiar and Peter Read. They managed to reproduce the hexagonal flow pattern in a container of water. The effect seen is easy to create when a jet stream of fast moving fluid is inserted inside a slower spinning field. The ratio causes the polygons.

Having said that, the phenomenon is still suspicious. The jet stream composing the hexagon has to be maintained at a fairly constant speed. Any energy loss has to be replaced, and replaced pretty exactly. Not too much and not too little. And over a prolonged period of time. Hard to see how such precision can be maintained with natural causes.

The other suspicious aspect is the fact that not only does this seem to be unique to Saturn, it is unique to Saturn's north pole. If it was a natural phenomenon, you'd expect to see it in more places.


Saturn's moon Titan is the largest of the Saturnian moons. Indeed it is much larger than Luna. It is the only satellite known to have a dense atmosphere, and the only solar system object other than Terra where there is clear evidence of lakes.

Oh, did we forget to mention that on Titan it rains natural gas, the lakes are made out of petroleum, and the sand dunes are like coal? As a matter of fact, just the visible lakes of Titan are estimated to contain 300 times the volume of Terra's proven oil reserves.

Ray McVay is using this amusing fact as the basis for his Conjunction universe.


Saturn's moon Iapetus looks like a giant walnut. Or like something formed in a giant mold, with a noticeable seam line. It is also suspicious that the ridge is precisely on Iapetus' equator. Iapetus is white on one side, and rock-colored on the other, with the ridge only on the rock side (though the white side does have a series of isolated mountain peaks along the equator). The ridge is about 1,300 kilometers long, 20 kilometers wide, and varies in height from 12 to 20 kilometers. The ridge does have lots of craters in it so it must be fairly ancient.

As always there are many theories but nobody knows for sure. Other than the UFO fans who are sure this is a second Death Star.

One theory holds that Iapetus was semi-molten due to the decay of aluminum-26 and had a rapid rotation of 17 hours. The rotation made Iapetus bulge at the equator. As Saturn's tidal forces braked Iapetus' rotation to the current 79 days, it cooled down fast enough to preserve the ridge bulge.

Another theory had that the ridge is an upwelling of icy material. If it was not along the equator, it would destabilize the moon's rotational axis. The Iapetus would wobble until the ridge was along the equator.

A third theory is that Iapetus originally had its own ring system, which would naturally have formed over the equator. As the ring material fell down, it would naturally fall on the equator.


Phil Plait is a famous astronomer, lecturer, and author. He runs the Bad Astronomy blog. When it comes to astronomy, he knows what he is talking about.

And when you ask him what is the weirdest moon he knows of in our solar system, he points at the moon of Saturn named Hyperion.

For a moon that is only 270 kilometers in diameter, it sure has lots and lots of craters. The craters are bizarre as well. The rims are sharp, the slopes are shallow, and the bottoms are flat. Astronomers are (pretty) sure this is because Hyperion is so un-dense that meteors do not blast out craters so much as they compress them (like sticking your finger into a block of Styrofoam). The result is quite strange, just look at the photo. Looks like a huge sponge.

Hyperion is one of the largest know object that is irregularly shaped (Proteus is the largest). If it was much larger, gravity would have crushed it into the shape of a sphere. Hyperion has a porosity of about 46%, which means it is less a solid moon and more a collection of rocks that happen to be flying in the same orbit.

And to top it off, its rotation is chaotic. Its axis of rotation wobbles so much that it is impossible to predict where it will be pointing at any given time. It wildly tumbles as it orbits around Saturn.


Haumea is a dwarf planet orbiting beyond Neptune's orbit. But this thing is not spinning like a top, no, it's spinning like a jet engine turbine.

Blasted planet rotates in a mere 3.9 hours, which is faster than any other known equilibrium body in the entire solar system, and faster than any known body larger than 100 kilometers in diameter. Spins so fast the planet is an ellipsoid twice as long as it is wide (1,920 × 1,540 × 990 km). Not bad for a planet with a mass of 4 × 1021 kilograms.

If you stood somewhere on Haumea's equator the centrifugal force from its rotation would almost entirely counteract its force of gravity. Reminds me of the planet Whirlygig from Charles Sheffield's Between the Strokes of Night

Actually, when I read about its discovery I thought I was reading Clarke's Rendezvous With Rama.

So the world soon forgot about Rama; but the astronomers did not. Their excitement grew with the passing months, as the new asteroid presented them with more and more puzzles.

First of all, there was the problem of Rama's light curve. It didn't have one.

All known asteroids, without exception, showed a slow variation in their brilliance, waxing and waning within a period of a few hours. It had been recognized for more than two centuries that this was an inevitable result of their spin, and their irregular shape. As they toppled end over end along their orbits the reflecting surfaces they presented to the sun were continually changing, and their brightness varied accordingly.

Rama showed no such changes. Either it was not spinning at all or it was perfectly symmetrical. Both explanations seemed equally unlikely.

The sunlight reflected from Rama was not, after all, absolutely constant in its intensity. There was a very small variation—hard to detect, but quite unmistakable, and extremely regular. Like all the other asteroids, Rama was indeed spinning. But whereas the normal 'day' for an asteroid was several hours, Rama's was only four minutes.

Dr. Stenton did some quick calculations, and found it hard to believe the results. At its equator, this tiny world must be spinning at more than a thousand kilometres an hour; it would be rather unhealthy to attempt a landing anywhere except at the poles. The centrifugal force at Rama's equator must be powerful enough to flick any loose objects away from it at an acceleration of almost one gravity. Rama was a rolling stone that could never have gathered any cosmic moss; it was surprising that such a body had managed to hold itself together, and had not long ago shattered into a million fragments.

An object forty kilometres across, with a rotation period of only four minutes—where did that fit into the astronomical scheme of things? Dr. Stenton was a somewhat imaginative man, a little too prone to jump to conclusions. He now jumped to one which gave him a very uncomfortable few minutes indeed.

The only specimen of the celestial zoo that fitted this description was a collapsed star. Perhaps Rama was a dead sun—a madly spinning sphere of neutronium, every cubic centimetre weighing billions of tons .

Three months later the space probe, rechristened Sita, was launched from Phobos, the inner moon of Mars. The flight time was seven weeks, and the instrument was switched to full power only five minutes before interception. Simultaneously, a cluster of camera pods was released, to sail past Rama so that it could be photographed from all sides.

The first images, from ten thousand kilometres away, brought to a halt the activities of all mankind. On a billion television screens, there appeared a tiny, featureless cylinder, growing rapidly second by second. By the time it had doubled its size, no one could pretend any longer that Rama was a natural object.

Its body was a cylinder so geometrically perfect that it might have been turned on a lathe—one with centres fifty kilometres apart. The two ends were quite flat, apart from some small structures at the centre of one face, and were twenty kilometres across; from a distance, when there was no sense of scale, Rama looked almost comically like an ordinary domestic boiler.

Rama grew until it filled the screen. Its surface was a dull, drab grey, as colourless as the Moon, and completely devoid of markings except at one point. Halfway along the cylinder there was a kilometre-wide stain or smear, as if something had once hit and splattered, ages ago.

There was no sign that the impact had done the slightest damage to Rama's spinning walls; but this mark had produced the slight fluctuation in brightness that had led to Stenton's discovery.

The images from the other cameras added nothing new. However, the trajectories their pods traced through Rama's minute gravitational field gave one other vital piece of information—the mass of the cylinder.

It was far too light to be a solid body. To nobody's great surprise, it was clear that Rama must be hollow.

The long-hoped-for, long-feared encounter had come at last. Mankind was about to receive its first visitor from the stars.

From RENDEZVOUS WITH RAMA by (Sir) Arthur C. Clarke (1973)

Comet Hartley 2

NASA's EPOXI space probe flew by comet Hartley 2 to do some observations of the hyperactive comet. The skittish thing was moving most erratically, which gave NASA a real challenge to intercept it with the space probe.

However, the probe did spot something extremely odd.

"...on its larger, rougher ends, the comet's surface is dotted with glittering blocks that can reach approximately 165 feet (50 meters) high and 260 feet (80 meters) wide. The block-like, shiny objects, some as big as one block long and 16 stories tall, appear to be two to three times more reflective than the surface average."

Which makes me think of mirror-plated TMA-1s, shiny versions of the black monoliths from the movie 2001 A Space Odyssey and 2010 The Year We Make Contact.


Astronomers are not as lucky as chemists or physicists. They can do experiments, astronomers cannot. A chemist can mix a few chemicals and see what happens, but an astronomer cannot, say, set Jupiter and Saturn on a collision course.

Or at least they couldn't before the invention of computer modeling. Using equations and lots of computer time, they can set Jupiter and Saturn on a collision course and see what happens.

This works marvelously for all sorts of astronomical questions. Until one tries to model the early evolution of our solar system. If you try to model a solar system like ours with four gas giants (Jupiter, Saturn, Uranus, and Neptune) when the simulation settles down, it does not look like our solar system. Not even close.

SwRI researcher David Nesvorny wrestled with this problem, and might have found a solution. Four gas giants won't work in the simulation. But five will. The simulation settles down into a something that remarkably resembles our solar system, and in the process the fifth planet is flung into interstellar space.

So if Dr. Nesvorny is correct, there is a primordial planet from the birth of the solar system in the abyss of deep space. And it is still out there. Waiting.

Oh, and did I mention that researchers from the University of Louisiana discovered that the spacing of comets in the Oort cloud is not as it should be? They calculate that this can be explained if there exists an as-yet undiscovered gas giant planet lurking in the fringes of the Oort cloud. Shades of the Nemesis theory!

Kapteyn's Star

Kapteyn's Star was considered to be a rather run-of-the-mill red dwarf star about 3.9 parsecs (12.8 light-years) away from Terra (though Jacobus Kapteyn was sufficiently impressed by its high proper motion that he named it after himself. It has the second highest proper motion after Barnard's Runaway Star).

Then astronomers discovered it was freaking old, 11.5 billion years old or a mere 2 billion years younger than the entire universe. Sol is only about five billion years old.

Its high proper motion, the fact it is moving retrograde, and its range of elemental abundances lead astronomers to conclude that it was originally part of Omega Centauri, the old dwarf galaxy that the Milky Way grabbed and gobbled up.

Kapteyn's Star 3.9 parsecs (13 light-years) away from Terra. But it was only 2.2 parsecs (7 light year) away a mere 10,800 year ago, about the time our Mesolithic ancestors were busy inventing agriculture.

And in 2014 astronomers observed convincing evidence of two low mass planets, Kapteyn b and Kapteyn c. Kapteyn b is currently the oldest known potentially habitable planet.

Well, better Kapteyn's Star than Cthulhu's Star.

Collision Course Stars

Scholz's star

Scholz's star (full designation WISE J072003.20-084651.2) is a binary star system with a dim little spectral class M9 and an even dimmer T5 brown dwarf. It is currently about 17 to 23 light-years away.

But it wasn't always. About 70,000 years ago it came screaming past the solar system at about 80 kilometers per second, narrowly missing Sol by only 0.82 light-years (52,000 AU). While the stars proper only passed through the fringe of the Oort Cloud, their gravitation field probably perturbed every comet on this side of Sol.

Scholz's Star was within 100,000 AU of Sol for about 10,000 years. Unfortunately even at its closest it would have been far too faint to see (apparent magnitude of about 11.4, about 100 times fainter than the dimmest star visible to the naked eye). However M-dwarf stars often flare, so it might have been visible for periods of minutes to hours.

Comets perturbed from the Oort cloud will require roughly 2 million years to get to the inner Solar System. So you can expect a deadly hail of comets to plaster every planet in the system in about 1.93 million years.

Scholz's star passage probably did not have anything to do with the Population bottleneck that happened during the Toba Catastrophe, though both happened suspiciously at about the same time. It would be perfectly acceptable for a science fiction author to postulate a connection for the sake of their novel, since it is enough of an unbelievable coincidence that the author will have plenty of justification. Besides it might actually be true. There is a difference between "it is flat out impossible" and "scientists can think of no known mechanism which could cause it."

HIP 85605

HIP 85605 is a star that (may be) currently 16.1 light-years from Sol. If that distance measurement is correct (which is a big if) in about 350,000 years (240,000 to 470,000) it will come plowing through the solar system and wreck the place.

Its closest approach to Sol will be from 0.13 to 0.65 light-years (8,200 to 41,000 AU), passing between the Oort Cloud and the Kuiper belt. This is going to savagely perturb every single comet in the Oort cloud and every asteroid in the Kuiper belt. In less than 2 million years the barrage of comets and asteroids will make every planet and moon in the entire solar system look like it has terminal acne and Terra's biosphere will suffer the mother of all mass extinctions.

Or maybe not. The distance of 16.1 looks suspiciously close to astronomers, it would fit the Hertzsprung-Russel diagram much better if it was about 200 light-years away. The distance was determined by the Hipparcos detector, which might have been confused by glare from a nearby star. If the latter distance is the correct one, HIP 85605 will never get closer to Sol than a very safe 30 light-years, and that in a remote 2.8 million years.

Gliese 710

What has a spectral class of K7V, a mass of 60% of Sol, a velocity of 18.8 kilometers per second, and is heading straight at us? Why, the star Gliese 710, of course. But don't panic, it is about 19 parsecs away (62 light-years), so we won't have to worry for another 1.4 million years.

As nearly as the astronomers can calculate, Gliese 710 is not going to pass closer than about 0.88 light-year (0.27 ± 0.17 parsecs). This will send it right through the Oort cloud on the edge of the Solar System, sending a barrage of incoming comets. This will create results ranging from a mild 5% increase in cratering to extinction-level carpet bombing of every single planet and moon. Keep in mind that it will take about 2 million years for the perturbed comets to reach the inner Solar system, so the fun won't start until about 3.4 million years from now.

But the astronomers are not really sure since that is a long trajectory to calculate and they do not have much of a back trace. It is not impossible for Gliese 710 to actually penetrate the Solar system, passing within 1,000 AU of the Sun. Or even closer.

And in any event, the fact that Gliese 710 is aimed so closely at the Sun is quite suspicious. In his novel Eternal Light, author Paul McAuley suggests that the star was indeed aimed at the solar system by alien intelligences.

Gliese436 b

Gliese 436 is a star about 10.1 parsecs away from Terra. In 2004 the Neptune-sized planet Gliese 436 b was discovered orbiting the star.

The weirdness is that the freaking planet is covered in red-hot ice.

There is plenty of water, but the planet's gravity smashes it into something called Ice X (ice-ten). Among its many amusing properties, it has a melting point of over 725°C.

Therefore, despite the fact that the planet's surface is broiling at about 439°C, the blasted ice refuses to melt.

HD 69830 c

The planet HD 69830 c has the most glorious Zodiacal Light show known to science.

This is because the primary star has an asteroid belt twenty times as dense as the one in our own solar system. Some estimates put it at one thousand times as bright as our zodiacal light, which would make the the Milky Way in the sky look about as bright as a half-dead firefly.

Of course such a dense asteroid belt means that in addition to nightly meteor showers, the planet will probably be at risk for Dinosaur Killer asteroid strikes on alternate Thursdays.

But it will be a big attraction for asteroid miners, looking for the mother load.

The Asteroid Mining Company followed WarnOil's lead. Iron and nickel, of course, and a few other metals, were available in plenty in Sol's asteroid belt; but a great many other highly important metals, particularly the heavier ones, were not. Wherefore the Asteroid Mining Company changed its name to Galactic Metals, Incorporated, and sent hundreds of prospectors out to explore new solar systems. These men, too — hard-muscled, hard-fighting, hard-playing hard-rock men all were rugged, rough, and tough.

They found a sun with an asteroid belt so big and so full of chunks of heavy metal that it was all but unapproachable along any radial line anywhere near the plane of the ecliptic. This sun's fourth planet, while it was Tellus-Type as to gravity, temperature, water, air, and so forth, was much richer than Earth in metals heavier than nickel. Whereupon Galactic Metals pre-empted this metalliferous planet, named it "Galmetia", and proceeded to stock it with metalsmen — a breed perhaps one number Brinell harder even than Elbridge Warner's oilmen.

From SUBSPACE EXPLORERS by E. E. "Doc" Smith (1965)


Epsilon Lyrae is a double star system about 50 parsecs distant in the constellation Lyra. The two stars are ε1 and ε2, separated by 10,500 astronomical units (0.17 light-years). Their orbital period is several thousand years.

Upon closer observation, it turns out that ε1 and ε2 are both double stars themselves! The ε1 stars are separated by 116 AU and have an orbital period of 1804.41 years. The ε2 stars are at 121 AU and 724.307 years.

All of the stars are spectral class A, which are super bright and super short-lived. These stars believe that one should live fast, die young, and leave a good-looking corpse. Which means they will probably gutter out before native life has a chance to evolve in any of their solar systems.

In the night sky of Terra a few degrees away from Epsilon Lyrae is what seems to be another double-double: Σ2470 and Σ2474. But they ain't. While ε1 and ε2 are orbiting each other, the two Σ stars are a whoppling 350 parsecs separated. They have absolutely nothing to do with each other except they appear to be close in Terra's night sky. In fact, Σ2470 might not even be a binary at all, those two stars might also appear close but it is an optical illusion.

HD 140283

HD 140283 aka "Methuselah Star" is currently the oldest known star.

A simplistic analysis of its age leads one to believe it is 14.3 billion years old, which does not make sense since the universe is only 13.83 years old. Astronomers, after refining (i.e., fudging) their analysis now conclude it is 13.6 billion years old, or a mere 230 million year younger than the universe.

Since the Milky Way galaxy is only 13.2 billion years old, HD 140283 must have formed elsewhere and was later swallowed by our galaxy.

It is only 58 parsecs (190 light-years) away, which is far too close if it contains some eldritch cosmic horror from the dawn of creation.

KIC 8462852

KIC 8462852 is an unassuming spectral class F3 V/IV star approximately 454 parsecs (1,480 light-years) away. It seemed like just another run-of-the-mill class F3 star.

Until the Kepler Space Telescope started looking at it.

In an attempt to cope with the flood of data, the Kepler team took a tip from the Galaxy Zoo project and started an organization where civilian astronomy fans could comb through the data to find things that were quote "odd" unquote. Currently human beings are zillions of times better at spotting something odd than computer software, since it is almost impossible to explain to a computer what "odd" is. The Kepler team created the Planet Hunters

And like the Galaxy Zoo, the Planet Hunters project has paid off. In 2011 several members raised the alarm that the star KIC 8462852 was not just odd, it was downright bizarre.

The Kepler Space Telescope was designed to spot exoplanets, mainly by observing when a planet-sized object eclipses its parent star. Mature solar systems only have around ten planets or so, thus eclipses are rare events.

Immature solar systems are wall-to-wall asteroid belts slowly forming into planets, and thus have lots of eclipses. But you can spot immature solar systems by how brightly they shine at infrared. The asteroid belts engulf the entire system in a huge cloud of dust, which glows in the infrared band.

KIC 8462852 has lots of eclipses, but does not shine in infrared. This means it is a mature solar system (implying rare eclipses) that somehow has lots of eclipses.

What's more, eclipses by planets typically dim the star's light by under one percent. But from KIC 8462852 one of them was 15% and another was a whopping 20% ! A planet the size of Jupiter might dim the star by 1%, you'd need something about half the star's size to drop it 20%. Out of the 150,000 stars that the Kepler Space Telescope has observed, this is the only star with such an extreme light curve.

Even worse: the eclipses are aperiodic. Since eclipses are generally caused by an object orbiting something, they are by definition periodic: they happen at regular intervals. Aperiodic eclipses must be caused by a more complicated mechanism.

What the heck is going on?

In their paper T. S. Boyajian (who oversees Planet Hunters) and twenty-eight other people examined the possibilities. They studied and ruled out several scenarios: defects in Kepler, debris from an asteroid belt pileup, two planets colliding (like when Theia smacked into Terra and created Luna). None of them fit the facts.

Except for one. If another star passed through KIC 8462852 Oort cloud this would trigger a demolition derby of comets, which could explain the eclipses. As it turns out there is a small star about 1,000 AU away that could be the culprit.

The fly in the ointment is that such a comet smash up would have had to have happened within a short time span, about two years. The collision would have had to occur between observations from the WISE observatory and a large dip in flux (nearly 15%) seen in later Kepler observations. The chance that this happens just when we humans have telescopes to see it is literally astronomical.

Another fly in the ointment is that it is difficult to believe a swarm of comets could reduce the star's light by 20%.

Associate Professor of Astronomy and Astrophysics at Penn State Jason Wright is of the opinion that the long odds forces one to consider the dreaded "third-rail" of astronomy, the SETI hypothesis. In other words, he is not saying it is was aliens... but it was aliens.

Understand, Dr. Wright isn’t some wild-eyed crackpot; he’s a professional astronomer with a solid background.

SETI researchers have long suggested that we might be able to detect distant extraterrestrial civilizations, by looking for enormous technological artifacts orbiting other stars. Wright and his co-authors say the unusual star’s light pattern is consistent with a “swarm of megastructures,” perhaps stellar-light collectors, technology designed to catch energy from the star. Maybe even a Dyson Swarm under construction.

Dr. Wright said “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.” He and his associates are working on a paper, a pre-print can be found here.

Dr. Boyajian is now working with Dr. Wright and Dr. Andrew Siemion (UC-Berkeley) on a proposal to study KIC 8462852 at radio frequencies that could implicate the workings of a technological civilization.

Dr. Wright dubbed KIC 8462852 "Tabby's Star", after lead author Dr. Tabetha S. Boyajian.

Late breaking news, Dr. Bradley Schaefer looked at some historical data on KIC 8462852 and found more weird behavior. In his paper he details how the evidence from archival photographic plates circa 1890 to 1989 reveal that KIC 8462852 has been growing dimmer at the rate of 0.165±0.013 magnitudes per century. This is completely unprecedented for any F-type main sequence star.

This blows the comet theory right out of the water. The centuries long dimming and the recent dimming have to be due to one mechanism. For comets to do this would take an estimated 648,000 giant comets (each with 200 km diameter) all orchestrated to pass in front of the star within the last century. That ain't gonna happen, not naturally at any rate.

This has to be the result of some ongoing process with continuous effects. The SETI theory is getting harder and harder to avoid. Blasted thing might actually be a Dyson Swarm under construction after all.

RX J1856.5-3754

RX J1856.5-3754 is the closest known neutron star. The estimated distance is 120 parsecs (400 light-years).

It is thought that it formed when its companion star went supernova approximately one million years ago. This gave the star a velocity of 108 kilometers per second. It is one of the The Magnificent Seven.

WASP-12 b

WASP-12 is a yellow dwarf star about 871 parsecs away. Apparently the star is hungry, because it is devouring its planet WASP-12b

The planet has the misfortune of being far too close to its parent star, only 0.01 AU away. By way of comparison, the solar system's innermost planet Mercury orbits at a healthy 0.39 AU. Mercury takes 88 days to orbit Sol, WASP-12b orbits its primary in only 26 hours.

WASP-12's gravitational tides are squeezing the planet into an egg-shape. The squeezing causes so much internal friction that the hot planet has inflated in size. The size has increases so much that the planet's gravity cannot hold it together. The star is sucking off the planet's surface at the rate of six billion metric tons per second. The material does not immediately fall into the star, instead it forms a ring which is gradually spiralling down to its doom.

At this rate the entire planet will be gobbled up in a mere ten million years. As usual, this sounds like a long time to a human being, but it is only about 1/500th the current age of Terra.

Aquila Novae

Back in 1968, Sir Arthur C. Clarke noticed something odd.

According to Norton's Star Atlas, there have been twenty fairly bright novae between 1899 and 1936. No less than five of them have been in one small area of the sky, in the constellation Aquila. There were two in a single year (1936), and the 1918 Nova Aquila was one of the brightest ever recorded.

What's going on in this constellation? Why did 25 percent of the novae in a forty-year period appear in only 0.25 percent of the sky? Is the front line moving in our direction?

TROUBLE IN AQUILA by Sir Arthur C. Clarke (1979)

Before he wrote that article, he had used the idea in a short story called "Crusade" in 1968. In the story, something powerful and xenophobic is blowing up stars, and is gradually approaching Earth.

Erik Max Francis did an analysis with Mathematica. He pretty conclusively proves that the clustering in Aquila is due to the fact that it denotes an area of the sky that overlaps part of the galactic core. So there are more novae in Aquila because there are more stars of any kind in that general area. He figures that the centroid of the novae that Clarke noticed is roughly at Right Ascension 18h, Declination -30°

Vanishing Stars

A comparison of old and new star catalogs shows that some objects seem to have gone missing.

An international research group led by Beatriz Villarroel from the Nordic Institute for Theoretical Physics in Sweden and the Institute for Astrophysics on the Canary Islands reports something strange in the current issue of The Astronomical Journal. They compared star maps from the 1950s with recent surveys, and discovered that 100 previously catalogued stars cannot be found anymore.

The group’s project, called Vanishing and Appearing Sources during a Century of Observations (VASCO) has been comparing mapped stars listed in the U.S. Naval Observatory Catalogue (USNO) B 1.0, dating from the 1950s, with those in another, more recent sky catalog, the Pan-STARRS Data Release (DR1). A total of 150,000 objects were found in the older catalogue (which lists 600 million stars) that did not have a readily identifiable counterpart in the new star survey, even though the Pan-STARRS Data Release includes stars that are five times less bright than the faintest light sources included in USNO. Of these 150,000 anomalies, the authors visually inspected 24,000 candidates and discovered that 100 of these point sources of light appear only in the older star survey. And since then, apparently, they’ve vanished.

Certainly, the most parsimonious explanation for the missing stars is that they are natural phenomena such as extremely flaring dwarf planets, failed supernova, or stars that might directly collapse into a black hole. But there seem to me too many anomalies to explain all the vanished stars as known natural phenomena. In their current paper, the authors themselves discuss the possibility that they’re seeing unknown phenomena, or that the vanished “stars” could be relics of technologically advanced civilizations, particularly the theoretical mega-engineering projects known as Dyson spheres.

Perhaps the missing objects are signs of an advanced civilization. But they’re probably not Dyson spheres. First, it would be hard to explain why and how such a giant construction project, completely shading out the light of the host star, could be done within the short period of less than a century. But more importantly, Brooks Harrop and I showed nearly 10 years ago that “traditional” Dyson spheres are not gravitationally stable. Even if one could be built near a star like our Sun, it would require more total mass than is available in all our Solar System’s planets, moons, and asteroids.

So what are the missing stars? A few might be explained as flaring stars whose brightness dropped below the detection limit, or stars that collapsed directly into a black hole. A large portion, however, might represent new stages in the life cycle of certain stars or new stellar phenomena that have not yet been seen. That by itself would be an exciting topic to investigate.

Another intriguing question: Where are the missing stars? Are they at the same location, just not emitting light anymore? Or perhaps they’ve moved to some other location. If the latter, could some of these represent huge starships, the size of moons or planets, that moved outside the field of view? This, of course, is a highly speculative suggestion. But it would address the hotly discussed Fermi Paradox, and would, in principle, be testable. If these “missing” light sources represent giant starships, some should appear in new star surveys in some other part of the sky. In an ideal case, we might even be able to track their trajectories through time. It would be challenging, no doubt, to pick out such motions against other background movements in space, like those of stars spinning around the center of their galaxy. Nevertheless, my suggestion to the authors is to focus their future work on light sources that suddenly appear in new star surveys, and see whether they can be correlated to the stars that vanished.

In her paper, Villarroel suggests another very promising direction for future research—to search for clusters of missing stars, which, if they exist, could be related to new natural phenomena in a particular region of space, or perhaps to activities of an extraterrestrial civilization. Either way, the authors have turned up something that may become very important for both astrophysical and SETI investigations.

Horsehead Nebula

The Horsehead Nebula is an absorption nebula which is part of the Orion Molecular Cloud Complex approximately 460 parsecs (1500 light-years) from Terra. It was discovered in 1888 by Scottish-American astronomer Mrs. Williamina Fleming.

But it is widely known since practically nobody can view it without thinking "Lookit the Horsie!"

Since it is one of the most identifiable of dark nebula, it is a favorite of science fiction authors who want a fabulous location as a backdrop, or who just want to do some name-dropping to show how astronomically erudite they are.

  • The Stars, Like Dust by Isaac Asimov: The novel takes place mostly in the Nebular Kingdom planets around the Horsehead Nebula, which have been conquered by the Hegemony of Tyrann.
  • The Ship Who Sang by Anne McCaffrey: It is used as a tongue-in-cheek heroic destination: "To the Horsehead Nebula and back!"
  • Space Pirate Captain Harlock by Leiji Matsumoto: Mazone warrior Akias sets a trap for Harlock in the Horsehead Nebula
  • The Hitchhiker's Guide to the Galaxy by Douglas Adams: Zaphod Beeblebrox steals the Improbability Drive prototype ship Heart of Gold and aims for the Horsehead Nebula. Eventually they reach the dark heart and discover the planet Magrathea.
  • Ancient Shores by Jack McDevitt: An ancient stargate is discovered on a Sioux reservation in North Dakota. The planet on the other side has a ring-side seat to the Horsehead Nebula.
  • Doctor Who: In the episode "Planet of the Ood", the Doctor visits the Ood homeworld. The world lies in Mutter's Spiral (Milky Way Galaxy) in the midst of the Horsehead Nebula.
  • Mass Effect and Mass Effect 3 video games: the "Horse Head Neblua" contains several star systems which can be visited by the player.
  • Widget: The eponymous alien protagonist is from the Horsehead Nebula.
  • Malo Korrigan and the Space Tracers: In the episode "Old Soldier", Korrigan's ship the Starduke breaks down in the midst of the Horsehead Nebula.

      It was very difficult not to look at the visiplate. They’d be Jumping again soon, through that ink.

     Biron said absently, ‘You know why they call it the Horsehead Nebula, Gil?’
     ‘The first man to enter it was Horace Hedd. Are you going to tell me that’s wrong?’
     ‘It may be. They have a different explanation on Earth.’

     ‘They claim it’s called that because it looks like a horse's head.’
     ‘What’s a horse?’
     ‘It’s an animal on Earth.’
     ‘It's an amusing thought, but the Nebula doesn't look like an animal to me, Biron.’
     ‘It depends on the angle you look at it. Now from Nephelos it looks like a man’s arm with three fingers, but I looked at it once from the observatory at the University of Earth. It does look a little like a horse's head. Maybe that is how the name started. Maybe there never was any Horace Hedd. Who knows?’

(ed note: in the Wikipedia article is a wry note about the Asimov novel:

In his fable of the Horace Hedd folk etymology illuminating the limitations of geocentrism, Asimov outsmarted himself. From his earlier Galactic Empire novel Pebble in the Sky it is clear that the English language is no longer spoken either on Earth or in the larger galaxy: ... the woman [a resident of Earth's far future] spoke in no language Schwartz [a 20th-century Chicago man thrown forward through time] had ever heard.[20] The Horsehead/Horace Hedd pun only works in an anglophone galaxy. In his critique of geocentrism, the author neglected his own unconscious anglocentrism.


From THE STARS, LIKE DUST by Isaac Asimov (1951)

The Deadly Thing at 2.4 Kiloparsecs

This was a bit of speculation from Dr. David Brin that he wrote up in an article in the May 1984 issue of Analog magazine.

He used the (then current) data to infer that Earth suffered a mass extinction event with suspicious regularity, apparently happening every 197 million years (plus or minus 12 million years). There are no known natural terrestrial phenomenon that will happen with such regularity over such time scales. So he started examining astronomical phenomenon.

Sol (and Earth) takes 230 million years to orbit the center of the galaxy. This is close to 197 million years, but not close enough. But try postulating a Deadly Thing (such as a gamma ray burster or a large black hole with its radiation jets spraying the plane of the galaxy with glowing blue death) orbiting closer to the galactic center. If it orbits at a certain distance, the Sun will approach it every 197 million years. By taking reciprocals, you can determine that the Deadly Thing will have to have an orbit with a radius of 2.4 kiloparsecs (about 8,000 light-years). Sol has an orbit with a radius of about 10 kiloparsecs (about 33,000 light-years).

Just for the record, since Dr. Brin wrote his article, the new figure for the galactic orbital radius of Sol is 8.33 ± 0.35 kiloparsecs. So if you intend on using this in your novel you should recalculate appropriately.

As you would imagine, there are lots of questionable assumptions in this hypothesis. With these orbital radii, the closest the Deadly Thing ever comes to Earth is 7 kiloparsecs (about 23,000 light-years), so it has an unreasonably long range. It is also hard to imagine what could be so powerful and yet be undetectable by astronomers. Even more of a problem is that many scientist say there is no strong evidence for a regular occurrence of mass extinction events, and others have different values for the cycle length.

However, just because the assumptions are questionable does not mean they are wrong.

Regardless, this is still an excellent example of how starting with a few facts and interpolating using the laws of science can lead to entertaining results. SF authors are free to postulate other types of Deadly Things besides black holes, such as the Cthulhu star with its limited range telepathic death broadcast, or the Planet of Life-force Eaters With The Barely Long Enough Straw.

Dark Matter Planet

Rogue planets wandering the cold depths of space far from any star are very romantic in a science fictional sort of way. However, such planets are highly unlikely to contain life, unless said life forms enjoy living at a chilly 3°K.

But scientists Dan Hooper and Jason H. Steffen have an intriguing notion. One type of exotic particle (WIMPs) postulated as being behind the dark matter phenomenon would mutually annihilate other such particles, creating heat energy (i.e., WIMPs are their own anti-particle). WIMPs generally only rarely encounter each other, but they can be captured by the gravity of a planet. In the planet's core, WIMPs scooped up by the planet would quickly find other WIMPs and annihilate themselves, heating up the planet.

Hooper and Steffen calculate that since Terra is in a WIMP poor part of the galaxy WIMP annihilation would contribute a totally negligible one megawatt to Terra's heat. By contrast, Terra absorbs 100 quadrillion watts of heat from the Sun.

However, in the WIMP rich center of the galaxy, the heat goes up dramatically. They calculate that within 30 light-years of the galactic center, a planet with ten times Terra's mass could absorb enough WIMPs to generate 100 quadrillion watts. Thus such a rogue planet would be warm enough for life as we know it even with no sun nearby.

For people who take the long view, this would be ideal. A planet in a WIMP high region could be kept toasty warm for trillions of years, long after all the stars in the entire universe had burnt out.

Runaway Star

A runaway star is young star, usually of spectral type O or early B, with an unusually high space velocity relative to the surrounding interstellar medium (on the order of 100 kilometers per second). If you trace its path backward, you will find the star cluster that it got ejected from. They generally occur when two binary systems pass too close to each other, or if the star has the misfortune to be orbiting a star that goes supernova. Such stars are not traveling fast enough to escape the gravitational pull of the galaxy.

The best known are Naos (Zeta Puppis), and the trio AE Aurigae, 53 Arietis, and Mu Columbae, all of which are racing away at 100 kilometers per second on diverging paths from a comparatively small region in the Orion nebula. They probably were orbiting the star that went supernova about two million years ago, forming Barnard's Loop.

CW Leonis

CW Leonis (aka IRC +10216) is an elderly star about 120–150 parsecs away. But it is one of those runaway stars, since the blasted thing is streaking along at a good 91 kilometers per second. Please don't confuse it with CN Leonis aka Wolf 359, where Starfleet had the snot beaten out of it by a Borg Cube on stardate 44002.3.

In the image the star is hidden inside a sooty shell of gas about 84,000 AU in radius (0.4 parsec). The front edge of the shell forms the bow wake. In the image the star is moving from right to left.

The star is well on its way to becoming a white dwarf, as it blows off carbon-rich gas. Other than the fact it is moving as fast as a jack rabbit in front of a prairie fire, it is a pretty unremarkable star.

The poor innocent star had the misfortune to become an urban legend sometime in 2008.

Google Sky dumped lots of astronomical data into its sky view, to make it more interesting than just looking at white specks on a black background. Since CW Leonis is pretty much invisible by ordinary light, Google opted to use a false color infrared image. This used data from the IRAS infrared space telescope, which unfortunately had severe issues when it imaged the star. The innocent star became a huge ugly multicolored blob with two long tails that were scanning artifacts (basically lens flares).

Later in 2008 some clown who was either a True Believer conspiracy theorist or a troll in search of lulz went to WikiSky and labeled the object 'Nibiru'. Well, it is a wiki after all.

Nibiru is an imaginary planet that far too many credulous conspiracy theorists believe passes by Earth every 3,600 years, allowing the ancient astronaut god-like inhabitants to invade us in their flying saucers and enslave the entire human race. Thanks to that show-oaf on WikiSky throwing gasoline on the fire, to this day there are periodic outbreaks on conspiracy forums about how CW Leonis is comin' ta getcha and the end is nigh.

Hypervelocity Stars

Hypervelocity stars are runaway stars that are traveling fast enough to escape the gravitational pull of the galaxy, typically on the order of 1,000 kilometers per second. All currently known hypervelocity stars are over 50,000 parsecs away from Earth. Except for RX J0822-4300.

Hypervelocity stars are probably created when a galactic core star suffers a close encounter with the Sagittarius A* supermassive black hole at the center of the galaxy. Also known as the Star Yeeter.

SF authors can postulate that such stars are created by incredibly advanced aliens who like to travel. But there are implications. Consider, if there was a civilization powerful enough to accelerate their home star to 1000 km/sec; they must be running scared from something even more powerful.

Puppis A and RX J0822-4300

Puppis A is the remains of a supernovae about 2,000 parsecs away (7,000 light-years). It blew itself to smithereens about ten-thousand years ago (though the light of the supernova didn't reach Terra until about 3,700 years ago). While it appears to be part of the Vela Supernova Remnant, Puppis A is actually about four times farther away and being upstaged by Vela.

In the center of Puppis A is a neutron star named RX J0822-4300 aka "Cosmic Cannonball". Which should give you an idea of how fast it is going. The neutron star is flying out of the heart of the supernova like a bat out of hell at 1,500 kilometers per second or about 0.5% the speed of light. At that rate it will be out of the Milky Way galaxy in a mere million years or so.

Astronomers are still undecided about how RX J0822-4300 managed to get up to such hyperspeeds, they were under the impression that you needed something like a slingshot around the Sagittarius A* galactic core black hole to do that. Just sitting next to a supernova when it goes kablooey is not enough. Some muttered that perhaps RX J0822-4300 was actually a quark star. Alternatively astronomers never ever say something was caused by aliens, but it might be in the back of their minds.

However a 2012 astronomical analysis figured RX J0822-4300 ain't a hypervelocity star at all, they measure it at a relatively sedate 672 km/s. Which is barely possible with a supernova. Party poopers.


Novae are stars that periodically explode, generally a white dwarf devouring hydrogen from a companion star and getting indigestion. They typically emit about 6 x 1037 Joules of energy, and our galaxy has about 30 to 60 Novae explosions per year.

Supernovae are much worse.

Unlike the periodic burp of a nova, a supernova destroys the entire star, leaving nothing but a neutron star or a black hole (actually, a type Ia supernova leaves behind nothing). A supernova typically emits about 1 x 1044 Joules (roughly ten million times as much as a nova) or more than all the other stars in the galaxy put together. That amount of energy is termed one FOE (ten to the Fifty-One Ergs), which is a unit of supernova strength.

You don't want one of these detonating anywhere near Earth, not if you care about the place. Scientists figure that a supernova explosion occurs within 10 parsecs of Earth every 240 million years or so. Possibly the most recent one was Geminga, which occurred about 300,000 years ago, and was probably the reason that Sol is near the center of a low hydrogen void called the Local Bubble.

Here is a handy-dandy list of supernova candidates which are due to explode anytime from several million years from now to this time tomorrow.

WR 104

WR 104 is a Wolf-Rayet star, 2400 parsecs from Earth, and supernova candidate. Ordinarily that would be far enough away to be harmless. Unfortunately WR 104 just might be large enough to create a lethal gamma-ray burst. And there is some evidence that Earth is staring straight down WR 104's gun barrel, so to speak.

Gamma ray burst emerge along a supernovae's rotational axis. Astronomers measured WR 104's axis, and were nonplussed to discover that it was pointed within 16° of Earth. Right between the eyes. Later data suggested that the axis was only pointed within 30 to 40°, but they are still not sure.

Red Square Nebula

Star MWC 922 is dying, and like many such stars it is spewing gas. But unlike many such stars, it is forming a rectilinear square. The theory is that it is emitting gas in two cones, with the cones being almost perfectly at ninety degrees to our line of sight.

Or we are watching a Kardashev type II civilization building a Dyson sphere. The general rule is that almost all natural objects are curved, only artificial ones have square angles.

The nebula is approximately 1,500 parsecs away (5,000 light-years).

But ever since the first of the so-called "beacon stars" was discovered, at the end of the twentieth century, we have known that there were civilizations with access to energy sources incomparably greater than ours. Some of you will doubtless recall the incredulity of the astronomers — and later of the whole human race — when the first examples of cosmic engineering were detected in the Magellanic Clouds. Here were stellar structures obeying no natural laws; even now, we do not know their purpose — but we know their awesome implications. We share a universe with creatures who can juggle with the very stars.

LOVE THAT UNIVERSE by Sir Arthur C. Clarke (1961)

UY Scuti

UY Scuti is the current front-runner for the star with the largest known radius. The estimated radius is 1.188×1012 metres (7.94 astronomical units or 1,708 solar radii). Replace Sol with this monster and Jupiter would be burning up in UV Scuti's photosphere.

It is at a distance of 2,900 parsecs (9,500 light-years).

3C 397

3C 397 (aka G41.1-0.3) is a galactic supernova remnant about 33,000 light-years away. It exploded between 2,000 and 1,000 years ago.

But as you can see, much like Red Square Nebula, the blasted thing has suspicious square angles in it. Is this another example of a Type II civilization playing Lego with supernovae? You decide.

Local Bubble

The Sun has the misfortune to be located near the center of a huge region about 330 to 490 light-years in diameter called "The Local Bubble". The interstellar medium within the Local Bubble has a density of about 0.05 atoms/cm3, which is about ten times lower than in the rest of the galaxy. This makes a thin fuel source for a Bussard ramjet. The Local Bubble is thought to have been caused when the star Geminga went supernova about 300,000 years ago.

Late breaking news, it might not have been Geminga after all.

A 2002 paper by T. W. Berghoefer and D. Breitschwerdt suggest the Local Bubble was created by multiple supernovae in the B1 subgroup of the Pleiades when it was less than 100 parsecs away (300 light-years). The supernova might also be responsible for the Gould Belt.

Brian C. Thomas et al have calculated that of the supernovae that created the Local Bubble, there were two main events. One at 1.7 to 3.2 million years ago, and the other at 6.5 to 8.7 million years ago. On Terra, the radiation increase may be related to a minor mass extinction around the Pliocene-Pleistocene boundary.

View is looking down on the galactic plane. Sol is at center, labeled "The Sun". Coreward is to the right, Spinward is to the top. Map is approximately 124 parsecs square (400 light-years), which is plus or minus 62 parsecs from Sol.

Fig. 1. Local cavity and LB in the plane of the Galactic equator. The filled contours show the Na i distribution (Sfeir et al. 1999), with white used for low-density regions and dark gray for high-density ones. The black contour shows the present size of the LB as determined from X-ray data (Snowden et al. 1998), with the dashed lines indicating contaminated areas where the limits of the LB cannot be accurately determined. The hatched ellipse shows the approximate position of the Ophiuchus molecular cloud (de Geus et al. 1989; Loren 1989a, 1989b). The present and past x- and y-coordinates of the center of the three subgroups of the Sco-Cen association are shown. For LCC and UCL, the past positions shown are those of 5 and 10 Myr ago, while for US only the position of 5 Myr ago is shown. The dimensions of the filled ellipses indicate the uncertainties in the past positions. Coordinates are expressed in units of parsecs.

Translation into English:

View is looking down on the galactic plane. Sol is dot in the center. Coreward is to the right (labeled "To the GC"), Spinward is to the top (labeled "Rotation Direction"). Scale on the edges are in parsecs, map is area plus or minus 200 parsecs (652 light-years).

The black dotted line is the boarder of the Local Bubble. As near as I can tell the black square icon tracked with arrows (the Sco-Cen OB association UCL subgroup) is the same as the Pleiades subgroup B1 mentioned below.

Fig. 2. Sketch of the solar neighborhood seen from above the galactic plane. The center of mass position of Pleiades subgroup B1 is labeled with “B1”. The solid line, ending at the actual position of B1, provides the trajectory of the moving group during the past 30 Myrs in the epicyclic approximation (see Sect. 3); center of mass positions 13, 20, and 30 Myrs ago are labeled with -13, -20, and -30. Approximately 13 Myrs ago the most massive B1 star(s) (M ≈ 20 M) must have exploded. The local cavity contours as derived from Nai absorption line studies by Sfeir et al. (1999) are shown as thick solid lines (dashed lines denote directions of uncertain local cavity borders). As can be seen, existing B1 member stars (or at least some of them, given their spatial spread) should have crossed the region, which now forms the Local Bubble.

Translation into English:

View is looking down on the galactic plane. Sol is dot in the center. Coreward is to the right (labeled "GC"), Spinward is to the top. Scale on the axes are in parsecs, map is area plus or minus 200 parsecs (652 light-years).

The large gray disc is the Local Bubble. B1 is the Pleiades subgroup B1. It trails an arc showing its path through the galaxy, labeled with marks for -13, -20, and -30 million years ago. α Per (Alpha Persei Cluster), Pleiades cluster, Praesepe (Beehive) cluster, NGC 2451 cluster, IC 2391 (Omicron Velorum) cluster, and IC 2602 ( Theta Carinae or Southern Pleiades) cluster are marked.

Omega Centauri

Omega Centauri is a relatively nearby globular cluster. At least, they thought it was a globular cluster up until recently.

You see, the more astronomers studied Omega Centauri, the less it looked like a globular cluster. It is by far the largest of all of the Milky Way's globular clusters, about ten times as massive as all the other globular clusters. It does have an intermediate sized black hole in the core (4.0 × 104 solar masses). But the smoking gun is the population of stars it is composed of.

You see, apparently all globular clusters are formed at the birth of their parent galaxy, so all their stars are the same age, and all of them are metal poor. Since the stars of Omega Centauri are of wildly different ages and metallicities, most astronomers are sure it is not a globular cluster at all.

Instead, they have concluded that Omega Centauri is the core of a dwarf galaxy that the Milky Way galaxy grabbed and devoured several billion years ago.

A science fiction author could not help but wonder if some alien race living in the former Omega Centauri galaxy holds a grudge against the Milky Way galaxy, or considers the Milky Way a juicy vulnerable host organism Omega Centauri has infected. If either of these scenarios are true, the fact that Omega Centauri is about 4,840 parsecs (15,800 light-years) away is no comfort. You see, Kapteyn's Star was once a part of Omega Centauri, and that star is only 3.9 parsecs (13 light-years) away.

And Kapteyn's Star was only 2.2 parsecs (7 light year) away a mere 10,800 year ago, about the time our Mesolithic ancestors were busy inventing agriculture.


      Well, it looks like we’re going to have to look farther than we thought for intergalactic extraterrestrial life.

     Astronomers have long held out hope that Omega Centauri, a massive globular cluster just 16,000 light years away, harbors habitable exoplanets. Researchers estimate that 10 million densely packed stars lie within the cluster’s borders, so statistically speaking, it must house some habitable planets, right? Wrong. In fact, Omega Centauri’s stellar density is the reason why some scientists now suspect life doesn’t exist on any of its planets.

     A study submitted to The Astrophysical Journal July 31 highlights prominent exoplanet hunter, Stephen Kane, and his search for habitability in this compact sea of stars. But even though it’s the largest globular cluster in the Milky Way and relatively nearby, surprisingly little is known about its planetary population.

     “Despite the large number of stars concentrated in Omega Centauri’s core, the prevalence of exoplanets remains somewhat unknown,” said Kane, who teaches planetary astrophysics at the University of California, Riverside, in a press release. “However, since this type of compact star cluster exists across the universe, it is an intriguing place to look for habitability.”

     Kane, along with San Francisco State graduate student Sarah Deveny, used data from the Hubble Space Telescope to study 350,000 red dwarfs in the center of Omega Centauri. These stars are around the right age and temperature for exoplanets to exist within their habitable zones — the region where liquid water can be sustained on a planet’s surface.

Too Close For Comfort

     The duo calculated the habitable zone for each of these stars and found that, like the cluster itself, it’s a pretty tight squeeze. Due to the small and dim nature of red dwarfs, they give off little light and have habitable zones that only stretch about 46 million miles (74 million kilometers) from their surfaces. That’s just half the size of habitable zones surrounding stars like the Sun.

     The short distance between red dwarfs and their potentially habitable planets isn’t an issue, but their proximity to other red dwarfs is.

     In the core of Omega Centuari, only about 0.16 light years lie between each red dwarf. For comparison, the closest star to our Sun is Alpha Centauri, which sits a good 4.22 light years away. Since the stars are so compact, their gravitational forces end up interacting with one another, and consequently knocking each other’s planets out of orbit. The researchers estimate that these stars disrupt each other once every 1 million years or so, which doesn’t give their planets enough time to form and sustain life.

     “The rate at which stars gravitationally interact with each other would be too high to harbor stable habitable planets,” said Deveny, who co-authored the paper, in a news release. “Looking at clusters with similar or higher encounter rates to Omega Centauri’s could lead to the same conclusion. So, studying globular clusters with lower encounter rates might lead to a higher probability of finding stable habitable planets.”

     Astronomers might feel let down by the once promising Omega Centauri, but luckily, there are a whole slew of other globular clusters hanging around our galaxy.

Pistol Star

The Pistol Star is approximately 25,000 light-years from Terra in the direction of Sagittarius. Ordinarily a star at that distance would not be visible to the naked eye, were it not for the fact that the Pistol Star is about 1,600,000 times as luminous as Sol.

Well, actually you still can't see it with the naked eye because of all the interstellar dust clouds, but if it wasn't for all those pesky clouds the blasted thing is so luminous it would be a freaking fourth magnitude star. Even at a range of 25,000 light-years. The clouds defeated conventional telescopes but the Hubble Space Telescope finally spotted it in the early 1990's.

It radiates more energy in twenty seconds than our Sol does in an entire year.

The Pistol Star is a blue hypergiant and it currently the most luminous known star in the entire galaxy. It is expected to go kaboom as a supernova or hypernova real soon, at least as far as astronomical events go (one to three million years).

Galactic Habitable Zones

Charles H. Lineweaver, Yeshe Finner and Brad K. Gibson wrote an interesting paper entitled "The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way". Science 303 Issue 5654: 59-62 (January 2004). According to their analysis, if you are interested in regions of the galaxy where life as we know it can exist, there are good regions and there are bad regions. Specifically, the "Goldilocks zone" where life can develop is a torus shaped region centered on the galactic core. The inner edge is 7 kiloparsecs (23,000 light-years) from the core, and the outer edge is 9 kiloparsecs (29,000 light-years) from the core. Earth's sun Sol orbits right in the middle, at 8.33 ± 0.35 kiloparsecs (about 27,000 light-years).

Inside 7 kiloparsecs, the incidence of supernovae is so large that the radiation would fry any planets developing life. Outside of 9 kiloparsecs, there are not enough heavy elements to form any planets. So the galactic habitable zone is the only place where life as we know it can develop. At least according to the paper.

Keeping in mind that if one is dealing with life unlike we know it, all bets are off.

Sagittarius A*

Sagittarius A* (pronounced "Sagittarius A-star", abbreviated Sgr A*) is an object visible by radio waves at the core of our own Milky Way galaxy. It is probably the accretion disc around the supermassive black hole which probably exists at the core as well. The presumed black hole is about 8,000 parsecs (26,000 light-years) away from us, and has a mass of about 4.1 million solar masses.

Unlike Sagittarius A*, we cannot actually see the black hole, because there is too much interstellar gas and dust in the way, along the spiral arms (yes, I know black holes are invisible because light cannot escape them, but the flood of space debris impacting the hole is not). But we are reasonably sure it is there. Astronomers have plotted the orbits of quite a few stars near the core, and determined that they are frantically orbiting something incredibly massive in the heart of Sagittarius A*. They can calculate the mass of the object, and its maximum radius, and the only possible natural object is a black hole. Possible artificial objects are left as an exercise for the reader.

The supermassive black holes at the cores of other galaxies are prone to emit large flares that last for several months. This is because about every 100,000 years the core black hole manages to pull in a hapless star close enough so it can be eaten. Astronomers have not seen Sagittarius A* flare like that, but one hundred thousand years is a long time between flares.

What they have seen are much smaller flares, which last only a few hours but occur daily. These are probably asteroids being consumed. And there was a larger flare about 300 years ago (inferred by the presence of a "light echo", nobody actually saw it happen). That flare was probably the death cry of a full sized planet.

Sagittarius A* is probably the source of all the Milky Way galaxy's Hypervelocity Stars. That's why they call it the Star Yeeter

Science fiction authors are free to speculate about a radiation-proof species of alien who have the misfortune to inhabit a planet spiralling into Sagittarius A*. They are likely to be all emo, angsty and depressed.

Fermi Bubbles

NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way -- a finding likened in terms of scale to the discovery of a new continent on Earth. The feature, which spans 50,000 light-years, may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."

At more than 100 degrees across, the structure spans more than half of the sky, from the constellation Virgo to the constellation Grus. It may be millions of years old.

A paper on the findings will appear in an upcoming issue of The Astrophysical Journal.

Finkbeiner and Harvard graduate students Meng Su and Tracy Slatyer revealed the bubbles by processing publicly available data from the satellite's Large Area Telescope (LAT). Their work expanded on previous studies led by Greg Dobler at the Kavli Institute for Theoretical Physics in Santa Barbara, Calif.

Fermi's Large Area Telescope is the most sensitive and highest-resolution gamma-ray detector ever orbited. Gamma rays are the highest-energy form of light.

The structures eluded previous astronomers studying gamma rays due in part to the so-called diffuse emission -- a fog of gamma rays that appears all over the sky. The emissions are caused by particles moving near the speed of light interacting with light and interstellar gas in the Milky Way.

The Fermi LAT team is constantly refining models to uncover new gamma-ray sources obscured by the diffuse emission. By using various estimates of the gamma-ray fog, including the Fermi team's, Finkbeiner and his colleagues were able to subtract it from the LAT data and unveil the giant bubbles.

"The LAT team confirmed the existence of an extended structure in the direction of the inner part of the Milky Way and we're in the process of performing a deeper analysis to better understand it," said Simona Murgia, a Fermi research associate at the SLAC National Accelerator Laboratory in Menlo Park, Calif.

The researchers believe that an important process for producing the Milky Way's gamma-ray fog, called inverse Compton scattering, also lights up the bubbles. In that process, electrons moving near the speed of light collide with low-energy light, such as radio or infrared photons. The collision increases the energy of the photons into the gamma-ray part of the electromagnetic spectrum.

The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way.

The bubbles also appear to have well-defined edges. Taken together, the structure's shape and emissions suggest that it was formed as a result of a large and relatively rapid energy release -- the source of which remains a mystery, Finkbeiner noted.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence that the Milky Way's black hole sports such a jet today, it may have in the past.

The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's central light-years several million years ago.

"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."

Finkbeiner noted that, in retrospect, hints of the bubbles appear in earlier spacecraft data, including the Germany-led Roentgen X-ray Satellite (ROSAT) and NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

The Milky Way appears as a relatively flat structure when viewed along its plane in visible light. Gamma-ray emission, however, paints a different picture: two huge structures billowing outward from the galaxy’s bulge like an enormous hourglass. Named the Fermi Bubbles, these structures are the result of the Milky Way’s supermassive black hole gorging itself on interstellar gas in the past. Using the Hubble Space Telescope (HST), astronomers have now determined just when these structured formed.

A team of astronomers led by Rongmon Bordoloi of the Massachusetts Institute of Technology has used distant quasars to trace the structure and motion of the northern Fermi Bubble, which rises 23,000 light-years above the plane of the Milky Way and contains enough cool gas to create 2 million Sun-size stars. By observing the ultraviolet light from 46 quasars with the Cosmic Origins Spectrograph (COS) on HST (and adding one quasar observation with HST’s Space Telescope Imaging Spectrograph), the team mapped out the motions of cool gas within the bubble to pin down its age: 6 to 9 million years.

Most galaxies contain a supermassive black hole at the center, and our Milky Way is no exception. Sgr A* resides in the Milky Way’s bulge and has a mass equivalent to 4.5 million solar masses. Today, Sgr A* is relatively quiet, accreting slowly as the galaxy ages. By contrast, quasars are young, massive supermassive black holes at the centers of galaxies in the early universe, sucking down huge amounts of gas and dust that shine brightly as the material is funneled into an accretion disk before finally passing into the black hole. Like these younger black holes, astronomers believe that our own supermassive black hole was once more active, at a time when the galaxy was still forming and material was more plentiful for accretion.

Sometimes, though, material doesn’t actually make it all the way into the black hole. Matter can escape along the black hole’s spin axis, exiting the area — and often the galaxy altogether — as huge outflows that span tens or hundreds of thousands of light-years. The Milky Way’s Fermi Bubbles are such an outflow; they were discovered in 2015 and named after NASA’s Fermi Gamma-Ray Telescope, which spotted them.

Learning more about the origins of these outflows requires information about their motion. “We have traced the outflows of other galaxies, but we have never been able to actually map the motion of the gas,” said Bordoloi in a press release announcing his group’s results. The work also appeared in the January 10, 2017 edition of The Astrophysical Journal. “The only reason we could do it here is because we are inside the Milky Way. This vantage point gives us a front-row seat to map out the kinematic structure of the Milky Way outflow.”

As the quasars’ light travels through the bubble to reach Earth, it highlights the gas in the bubble itself, allowing astronomers to determine information such as its chemical composition, temperature, and motion. The “cool” gas in the northern Fermi Bubble, which contains elements such as silicon and carbon, was clocked at 2 million miles per hour (3 million kph) and reaches temperatures of 17,700 degrees Fahrenheit (9,800 degrees Celsius).

Such cool gas is actually likely gas from the disk of the galaxy that has been swept up by and integrated into the outflow itself, which has temperatures of up to 18 million degrees F (nearly 10 million degrees C). It is these high temperatures that cause the gas to shine in energetic light, such as gamma rays.

Once the gas’ velocity — its speed and direction of movement — was measured, astronomers used this data to turn back the clock and pinpoint when the gas started moving. This origin is also the last known “big meal” enjoyed by Sgr A*, which hasn’t managed to suck down such a significant amount of matter ever since.

What we find is that a very strong, energetic event happened 6 million to 9 million years ago,” Bordoloi explained. “It may have been a cloud of gas flowing into the black hole, which fired off jets of matter, forming the twin lobes of hot gas seen in X-ray and gamma-ray observations. Ever since then, the black hole has just been eating snacks.”

Object X

A team of astronomers lead by Rubab Khan stumbled over something strange in the Triangulum galaxy (M33) about three million light-years away. The object had been known about for decades, but was considered just another dim uninteresting object. They were shocked to discover that while it was quite dim in the visible light and near-infrared spectrum, in the mid-infrared spectrum the blasted thing is the most luminous object in the entire freaking Triangulum galaxy. Nobody had ever bothered to look at it in mid-IR before, because as a general rule things that are dim in the near-IR are also dim in the mid-IR. Looking back at old astronomical photographic plates, they know that whatever it is, it has been dim since at least 1949.

A gentleman who goes by the handle TME points out that an object that is very dim in the visible spectrum but unusually bright in the IR spectrum is the signature of a Dyson sphere. Freeman Dyson himself pointed out the possibility in his paper Search for Artificial Stellar Sources of Infrared Radiation, and proposed that SETI scientists should conduct a sky survey for such anomalous objects.

Object X probably is not actually a Dyson Sphere, but it is not totally impossible. It certainly is the closest thing spotted to date. Which is close enough for Science Fiction purposes.

Red Spirals

This is another groundbreaking discovery made by the Galaxy Zoo project.

Ever since the early days of galactic astronomy, everybody knew that spiral galaxies were blueish and elliptical galaxies were redish. This is because spirals are young galaxies and thus have lots of young massive blue stars. Elliptical on the other had are elderly galaxies, and blue stars have a regrettably short lifespan (at least compared to the age of a galaxy). Ellipticals are old enough that all their blue stars have died or gone supernova, leaving only the long-lived red stars. They are also old enough that all their spiral arms have collapsed, leaving only a galaxy shaped like a US football.

Then the Galaxy Zoo project spotted a number of blue ellipticals. What the heck is going on here?

As it turns out, blue elliptical are spirals that have collided with another galaxy or supermassive black hole. Gravitational tides erased the spiral arms. So this is a young galaxy with blue stars whose arms have been prematurely collapsed. Makes sense.

Then the Zoo spotted red spirals.

That seems easy enough. If a spiral galaxy gives birth to many more stars than is usual, then after a while there are so many red stars that they overwhelm the light from the blue stars. The blue stars are still there, there just are not enough to give the spiral its characteristic blue color. If an astronomer examines the near UV spectrum of a red spiral galaxy, it looks the same as an ordinary blue spiral. The UV is the blue stars shining through.

EXCEPT … they found eight red spiral galaxies with almost no UV at all. True, if a spiral is edge-on, the UV can be blocked by dust in the galactic disk. But none of the them were.

And five of them have very high mid-Infrared emission (MIR emission) which is unheard of with spirals but common with ellipticals.

This is a problem. Nobody has a natural explanation.

However, relevant to our interests, there is a non-natural explanation. Aliens performing galactoengineering.

You see, from the point of view of life living in a galaxy, blue stars are a menace. They end their lives rather quickly in violent supernova explosions, resulting in black holes or neutron stars. Supernova can kill off all surface life on a planet up to 3,000 light-years away.

Blue stars are also wasteful. A red dwarf star can emit useful amounts of solar energy for up to 2.5 trillion years. Accursed blue stars don't live longer than 4 million years before they go bang, then black. So a red dwarf will emit solar energy for about 625,000 times as long as a blue star. Short-sighted blue stars figure they should live fast, die young, and leave a worthless corpse.

Here's the scifi part. If a galaxy is inhabited by an alien species close to Kardashev type III technology level, they might suppress the formation of high-mass blue stars. That way they wouldn't have to worry about supernovae blasting out radioactive death every few million years, and all the hydrogen that would be wasted making black holes and neutron stars would instead be used to make reliable red dwarfs cranking out solar energy for trillions of years.

Of course, astronomers living in other galaxies would wonder why this one was a red spiral.

Hanny's Voorwerp

The Sloan Digital Sky Survey took images of zillions of galaxies. So many that astronomers despaired at ever classifying them all. So they decided to enlist the help of civilians via the Galaxy Zoo project. Anybody could sign up, and do some simple classification of a few hundred galaxies. In most cases, the civilian volunteers were the first human beings to view the images.

This paid off, big time, in August of 2007. Hanny van Arkel, a Dutch school teacher, had been happily classifying galaxies for a few weeks. She classified IC 2497 as an anti clockwise spiral galaxy. Galaxy Zoo gave her a new galaxy, but she hesitated, then returned to the previous galaxy. IC 2497 was a spiral galaxy, but what in the universe was that green thing below it?

She asked on the Galaxy Zoo online forum and asked the other volunteers if they knew what it was. They didn't. As they discussed it, they started calling it "Hanny's Voørwerp", where voørwerp is the Dutch word for "object".

In January 2008, some of the real scientist behind the Galaxy Zoo got around to trying to identify Hanny's Voørwerp. They were flabbergasted to discover that they couldn't identify it either. University of Alabama astronomer Bill Keel said: "As far as we can tell, it's an unprecedented thing." Throughout the known universe "there is nothing else that's quite like it."

Naturally the voørwerp and the neighboring galaxy are the object of active astrophysical research, including a close in photo from the Hubble Space Telescope. The latest hypothesis is that it's the remnants of a small galaxy that was flash-illuminated by a quasar lurking in the core of IC 2497. But they are still not sure.

Late-breaking news: now that they know what to look for, astronomers have found eight more of the accurséd things. In all the cases, the nearby quasar is not bright enough to illuminate the green goblin, for some as yet unexplained reason the quasar made a bright ultraviolet flash in the past. So the green goblin is fossil light. The actual green part is thought to be the remains of a smaller galaxy gobbled up by the quasar.

Andromeda Galaxy

Everything seems to be on a collision course with everything else. Even our Milky Way galaxy and the Andromeda galaxy are due to collide in about three to five billion years. Some calculations suggest that there is a 50% chance that the Solar System will have its orbit altered so it is three times as far from the core, and a 12% chance that it will be ejected from the galaxy entirely.

But we won't care, because by that time the Sun will have swollen enough so that all the oceans of Earth will have evaporated.

RS Ophiuchi

I do love a good space explosion.

Supernovae were one of my first astronomical loves. Stars explode! Like, completely. And they blast off as much energy as billions of normal stars, sometimes shining as brightly as their host galaxy.

Then I learned about other types of catastrophic cosmic events. Solar flares. Gamma-ray bursts. Magnetars. Planet collisions. Galaxy collisions.

They're all amazing and cool and happily (generally) very far away. I've read about them, written about them (literally, I wrote the book about them), and even done some scientific research into them.

But then I read about an event recently … and after twenty minutes of leaning forward over my monitor scrutinizing several research papers, I fell back into my chair, eyes wide, neck hair standing up, and under my breath I muttered, "Holy &%^#%$@."

I'm talking about M31N 2008-12a. It's what's called a recurrent nova, a cyclically repeating epic blast. A nova is a seriously powerful explosion, but this one … well.

I've given an overview of how a nova works before, but I'll recap. You start with a white dwarf: a super-compressed ball of extremely hot and dense matter. These are actually the cores of stars like the Sun, once it gets up in age a bit. As it ages, the Sun will swell into a red giant, blow off its outer layers, and reveal its super-hot über-dense core. This'll have roughly half the mass of the Sun, but only be the size of the Earth. That's small.

If the white dwarf is part of a binary system, orbiting a normal star, it can siphon material off that other star. Either the second star has swollen up into a red giant itself and dumps material onto the white dwarf, or it blows a dense wind of material (like a super-solar wind) that falls on the white dwarf. Either way, material, usually mostly hydrogen, piles up.

Mind you, the white dwarf is massive and small. That means its surface gravity is crushingly strong, as much as half a million times stronger than Earth's gravity! So the material piling up on the surface is getting hellaciously squeezed. If enough piles up, the atoms can get so compressed that they will fuse together. This can happen all over the surface of the white dwarf all at once, essentially a thermonuclear bomb that releases as much energy as 100,000 times what the Sun does!

They are so bright they can be seen at great distances, appearing like a new star in the sky. Hence the term nova, Latin for "new” (and short for the old-fashioned term "stella nova” — "new star”).

Once the material blows away, things settle down, and the process can start up again. Matter piles up, BANG, material blows off, things settle, matter piles up, lather, rinse, repeat. If it takes less than about 100 years for the event to repeat, we call this a recurring nova. Quite a few are known in our Milky Way galaxy. We see them in M31, the Andromeda Galaxy, too.

And now we can talk about M31N 2008-12a. The name means it's a nova ("N”) in M31, and the first one ("a”) seen in December 2008. It was also found to be a recurrent nova, but not like any ever seen before: Instead of taking centuries or even decades between blasts, M31N 2008-12a explodes every year.

Every. Year. Literally, every 340 days or so. It's a white dwarf with a red giant companion, and the wind from the giant blows material onto the dwarf more rapidly than most other systems. It piles up more quickly, getting to critical mass in less than a year. That's incredible.

But there's more. Oh yes, there's more.

It's long been theorized that there should be a big cloud of gas surrounding recurrent novae. Some novae do have small nebulae surrounding them, the expanding gas blasting away from the eruption, but in this case we're talking much bigger. A normal nova might have something a light year or three across around it — in general that's about as far as it can get before ramming into the gas between the stars slows it to a stop.

But a recurrent nova is repeatedly blasting stuff off, continuously pumping more material into the cloud around it. This will give the nebula expansion more energy, allowing it to plow up more material, and get bigger.

A nebula this big, however, has never been seen.

Until M31N 2008-12a. Surrounding this episodically epic eructator is a bubble, a cavity carved out by previous eruptions. It's elliptical in shape, like a Tic Tac or a rugby ball, and it's slightly bigger than usual.

It's 450 x 300 light years across. At least.

Holy &%^#%$@.

That's huge. Vast. Analysis of the bubble indicates that very little of it is actually from the eruptive events; the vast majority is swept-up interstellar material. And there's a lot of it: probably several hundred thousand times the mass of the Sun.

Holy &%^#%$@!

No wonder astronomers are calling this a super-remnant.

But there's one more thing. Given the size, expansion speed, and mass of the bubble, the astronomers figure that the nova has been doing this routine for a while now. When they do the math they find that it likely has been exploding like this for the past million years.

Holy &%^#%$@!

Yeah, getting to that part of the paper is pretty much when my brain had had enough. That's violence on a scale that's nearly impossible to grasp; this nova explodes with the fury of 100,000 Suns every year and has done it for a million years. Wow.

If this object were in our own galaxy, the Milky Way, it would probably be one of the most celebrated objects in the sky! But it's in Andromeda, removed by 2.5 million light years, so faint that you need a pretty good telescope to see it at all. That's why it wasn't discovered until 2008.

And oh, there's one more thing.

The white dwarf that powers this ridiculously over-the-top event is very close to the upper limit of how big one can get. If they grow too massive, all the subatomic particles inside feel so much squeezing that they will fuse together. In some kinds of white dwarfs they'll collapse to form an even more dense neutron star. In a different kind, the elements inside the dwarf will fuse all at once, all of them, and the entire star detonates like a nuclear bomb the size of our planet. The release of energy is so profound it tears the star apart. It explodes, creating a supernova.

M31N 2008-12a is likely the later kind, and is already very near this upper limit. At the rate it's collecting material, it'll go supernova in something less than a million years. Compared to a human lifespan that's a long time, but to an astronomer, that's soon.

We won't be in any danger from it; it's far too far to hurt us. But it'll be quite a show; the star will go from being invisible to easily visible to the naked eye. And that'll put an end to its episodic nature; once it blows, it blows. It'll be gone. Nothing left except a huge cloud of debris expanding at a decent fraction of the speed of light.

And there's one more one-more-thing. The region around the white dwarf has been swept fairly clear of material, snowplowed up by the repeated explosions. In that vacuum, the debris will expand pretty freely. After a few centuries it'll slam into all that stuff previously pushed out, and when it does it'll energize the heck out of it. It'll blast out energy across the electromagnetic spectrum, and light the nebula up like a Christmas tree.

And when it does, our great-great-great-greatnth descendants will see it, and when they do, there's only one thing they can do.

Say, "Holy &%^#%$@!”

Dark Matter Bridge

Astronomer Noam Libeskind and his associates had just finished a long boring task of plotting the motions of most of the galaxies within 50 million light-years when they noticed something extremely odd.

The dwarf galaxies nearby the Milky Way galaxy, Andromeda galaxy, and the Centaurus A galaxy appear to be moving along a galactic superhighway. One that stretches from nearby our Milky Way galaxy all the way to the Virgo cluster of galaxies. Dr. Libeskind et al have concluded that there is a huge bridge of invisible dark matter at the center of the superhighway.

If so, this would explain a 40 year old astronomical conundrum. One would expect that all the dwarf galaxies astronomers can observe would be flying around randomly. But they are not. Instead they are mysteriously grouped into huge spinning planes.

The process of leaving a galactic superhighway of dark matter, exiting via an "off ramp" created by the Milky Way's gravity might be the cause of the dwarf galaxies forming into a spinning plane.

You can find more details in Libeskin's paper.

But any science fiction author worth their salt has already picked up on the terms "mysterious invisible dark matter" and "galactic superhighway", and their brain is buzzing with ideas about a secret method of intergalactic rapid transit.

Sleeping Beauty Galaxy

This is M64, the "Sleeping Beauty" or "Black Eye" galaxy. At first glance, it looks like an ordinary run-of-the-mill spiral galaxy, 17 million light-years from Terra.

However, in 1994 astronomer Vera Rubin made the astonishing discovery that, unlike every other known galaxy, the interstellar gas in M64 is not rotating in the same direction that the stars are. Well, most of it. As it turns out, the gas within 3,000 light-years of the center rotates starwise, but freakishly the gas from 3,000 to 40,000 light-years rotates counter to the stars. And right at the edge between the two regions is an area of intense star formation, as the gas in the two regions collide and are compressed. All the stars there are young, blue, and incredibly hot.

Astronomers are pretty sure this counter-rotation is due to M64 colliding with a smaller galaxy millions of years ago. The smaller galaxy was long ago gobbled up, only the rotating gas remains. could be a rather huge example of astroengineering done by an alien Kardashev type III civilization.

Stephan's Quintet

Astronomers want to know how far away various astronomical objects are, because otherwise you can't get any work done. Since we can't take a tape measure to the Andromeda galaxy, indirect methods have to be used.

In 1848 French physicist Hippolyte Fizeau noticed that the light from some stars was red-shifted. In 1912, Vesto Slipher discovered that practically all galaxies also had a red shift. And in 1929 Edwin Hubble formulated his famous Hubble's Law. The law basically said that by measuring a galaxy's red shift, you could calculate it's distance. A majority of astronomers were quite pleased. Now they could figure galactic distances.

However, the rest of the astronomers were quite angry.

You see, there are two major theories of cosmology: the Big Bang theory and the Steady State theory. Big Bang predicts that galaxies and other objects that are close to us will be different from those that are far away. Steady State on the other hand, predicts that they will be the same regardless of distance. If you arrange galaxies as if their distances were according to Hubble's Law, the close galaxies are different from the distant ones. Which should tell you the proponents of which theory were angry at Hubble's Law. There were other problems with the Steady State theory, but this problem was far to big to sweep under the carpet.

Desperate to salvage the Steady State theory, the proponents embarked on an all out effort to discredit Hubble's Law. And soon they discovered Stephan's Quintet.

They look like a nice group of five galaxies, wildly colliding with each other. They had been discovered in 1877, but the fun started in the 1960's when Geoffrey and Margaret Burbridge got around to measuring their red shifts. They all had a red shift indicating a distance of 340 million light-years or so. Except for NGC 7320, its red shift said it was at a distance of only 39 million light-years. So the other galaxies were ten times as far away, even though they appear to be interacting and therefore adjacent. Oops.

The Steady Staters started waving Stephan's Quintet like a bloody shirt, claiming it was proof positive that Hubble's law was baloney and Steady State was right after all. But other astronomers took a closer look at NGC 7320, re-examining the assumption that it was indeed associated with the other four. Yes, all the galaxies appear to be embedded in filaments torn from each other, but is it not possible that NGC 7320 is just a nearby galaxy that is upstaging the distant ones?

In 2000 the ironically named Hubble space telescope produced evidence that Hubble's law was correct after all, and the Big Bang theory was king. The telescope could resolve individual stars in NGC 7320, while the other galaxies were a distance-blurred mess. All main-stream astronomers accept the Big Bang theory, and Steady State has been relegated to the dust-bin of history.

But of course there are plenty of fringe people who still deny the evidence, as a cursory Google search will reveal. Any science fiction author who wanted to use Stephan's Quintet to overturn modern cosmology for plot purposes could find plenty of justification. Authors who want to pursue this further will find good material in the websites of Dr. Halton C. Arp which can be found here and here. (thanks to Rhys Taylor for those links)

The Star Bridge

3C 123

In a 1960 paper Dyson suggested that any really advanced civilisation could not allow its sun to squander all its energy into space, but would eventually surround it by a shell — not necessarily a continuous one, but a cloud of orbiting worldlets. These "Dyson spheres" could be detected by their infra-red radiations, and several searches have been made for such artefacts. Though they have so far been unsuccessful, perhaps the first evidence of extra-terrestrial civilisations would be not through radio signals but by the detection of similar examples of cosmic engineering. However, like ants crawling round the base of the Empire State Building, we might not recognise it . . .

A short pause while I release another bee from my bonnet. The cover of the February/March 1997 Astronomy and Geophysics, the journal of the Royal Astronomical Society carries a dramatic and thought-provoking illustration — a radio image of the gas-clouds expanding from the galaxy 3C 123. Their source is a strange-looking object that I can only describe as a gearwheel, some of whose teeth have been slightly displaced. Whatever its explanation, it's far too large to be a common-or-garden Dyson sphere.

From a review of IMAGINED WORLDS by Arthur C. Clarke (1997)

On 3C123, my guess would be that's some sort of imaging artifact. Interferometry can do all kinds of weird things to the beam shape.

From astronomer Rhys Taylor (2016)

Elder God Galaxies

There are two main types of galaxy: spiral and elliptical. Spiral galaxies are young virile galaxies, with plenty of stellar nurseries giving birth to new stars. Elliptical galaxies are tired old worn-out galaxies, composed of aging and ancient stars with no new stars being born.

Or at least that's what astronomers thought. Since this was common knowledge, nobody bothered to look. Astronomers studied all the light from a given elliptical galaxy at once, smearing together the light of all the individual stars into one spectrum.

Astronomers Alyson Ford and Joel Bregman were using Wide Field Camera 3 on the Hubble Space Telescope. This uses ultraviolet light, which just so happens to be capable of resolving individual stars in distant elliptical galaxies. They were quite startled to stumble over hot newly born stars and stellar nurseries in the decrepit old elliptical galaxy Messier 105. They are still trying to figure out where the heck the hydrogen is coming from. Elliptical galaxies have used up all their interstellar hydrogen. No hydrogen, no stellar nurseries.

Anyway, consider the inhabitants of such a galaxy. The old stars will be full of Kardashev type II civilization (aka "Star Gods") doing their darnedest to become type III civilizations. Sprinkled here and there will be a small number of young stars, inhabited by primitive civilizations (like ours) cowering in a galaxy filled with Eldar Gods.

Blazar OJ287

A Blazar is a species of Quazar which are the most powerful known objects in the entire universe. They are supermassive black holes in the cores of giant elliptical galaxies. As with all black holes, their incredibly powerful gravitational attraction sucks in any matter that gets too close. Some of it is swallowed, the rest is accelerated outward in two titanic beams of particles and intense radiation from the two poles of the black hole's rotational axis.

Astronomers are of the opinion that if neither beam is aimed at Terra we just don't see it, if it is aimed somewhat close to Terra we see a quazar, and if it is aimed straight at us we see a blazar. Quazars and blazars are all pretty much the same.

Except for Blazar OJ287. It is about 3.5 billion light-years away (and thus 3.5 billion years in the past), which is about average for quazars. It has a mass of 18 billion solar masses, the largest known, about six times larger than the runner-up. It has an eleven year periodic variation in its output which most astronomers agree is due to the fact that the black hole is actually two black holes in close orbit around each other. But none of those things are particularly strange.

What is strange is that there is Some Thing about 14 parsecs (about 49 light-years) from the binary black holes, right inside the radiation jet. How do we know it is there? Because the blasted thing is emitting cataclysmic flares of not visible light, not ultraviolet light, not even x-rays. No, it emits monstrous flares of gamma-rays. And astronomers are worried because they can't figure out what the heck it is.

The Great Attractor

Back in the 1980's a group of astronomers known as the "Seven Samurai" were quite startled to discover that there were a huge number of galaxies converging on a point about 250 million light-years away. There was nothing visible at the focus point, but all around it were galaxies madly colliding with each other and radiating large amounts of radio waves. The invisible object was dubbed "The Great Attractor". It had a huge mass (about 5.4 × 1016 solar-masses), and was apparently sucking in every galaxy within 200 million light-years or so, including our own.

This was quite fascinating to SF authors. Alan Dean Foster used it in his novel Flinx's Folly and Stephen Baxter used in it his novel Ring (part of the Xeelee Sequence).

This sort of fell apart in 2005. The Attractor falls into the part of the sky called the "zone of avoidance", meaning it is very difficult to observe since our own galaxy's spiral arms keeps getting in the way. But a later sky survey managed to do it, using improved equipment. As it turned out, the Great Attractor is still invisible and mysterious, but it has a mass that is only one-tenth the original estimate. Further: our galaxy is not being sucked into the Great Attractor. It is actually being sucked into an even more massive region beyond it called the Shapley Supercluster.

The Great Repeller

This is from the paper The Dipole Repeller

As mentioned above, astronomers knew that the galaxies within about 200 megaparsecs (650 million light-years, i.e., the ones they could measure accurately) were all frantically rushing towards the Shapely Supercluster. The local group of galaxies (that our Milky Way is a part of) is moving about about 631 kilometers per second (plus or minus 20 km/s) with respect to the cosmic microwave background.

However scientists Yehuda Hoffman, Daniel Pomarède, R. Brent Tully and Hélène Courtois did some careful measuring and discovered a troubling fact: the local group is moving about twice as fast as it should.

Again, this is actually a good thing. Isaac Asimov noted "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' (I found it!) but 'That's funny ...'"

Given the attraction of the Shapely Supercluster, minus the drag of all the galaxies on the opposite side of the local group, the group should be moving at about 300 km/s. Ah, do you see the assumption? When astronomers calculated the drag, they assumed that the density of galaxies per cubic megaparsec was the observed universal average.

What if there was an underdensity of galaxies on the opposite side?

If there were fewer galaxies behind the local group, there would be a lower level of gravitational drag. This would increase the effective attraction of the Shapely Supercluster, and could explain why the local group was moving twice as fast as it should be. It's like a tug-of-war. If the center of the rope is moving to the left faster than you figured, probably means that there are fewer people on the right side than you thought.

This would look like there was something repelling the local group, though that would be an illusion. The local group's motion is shown by the cosmic microwave background dipole anisotropy, which is a fancy way of saying that we can see one point (pole) in the sky that is the local group's destination (Shapely Supercluster), and a second pole which is what the group is running away from. There are two poles, technical term is "dipole."

So the scientists called the underdensity area the Dipole Repeller.

Alas, this means laypeople will read that name and mistakenly think "OMG!! There is a giant antigravity galaxy repelling our galaxy!!" In reality, the Dipole Repeller is more like a cosmic void with no galaxies in it.

The scientists plotted the motion of the galaxies and distribution of clusters to determine the flow patterns. They loop around but converge on the Shapely Supercluster.

By using painstaking mathematically analysis, the scientists could calculate the anti-flow patterns. These loop around but they converge on the Dipole Repeller. This pin-pointed its location. Which otherwise would be a problem. It is always easier to see a cluster of galaxies than it is to see a void empty of galaxies.

Eldar Black Holes

Adam Crowl had an amusing idea. A recent paper suggested that it is possible to have black hole(s) that are older than the universe.

Imagine that you have a cyclic universe, where a universe is born in a big bang, ages, then finally dies in a big crunch. then it is reborn in a new big bang. The paper states that it is possible for some black holes born in one cycle to avoid being gobbled up in the big crunch, and would then be present in the new universe born in the next big bang. The black holes would be older than the new universe since they were born in the prior universe.

Something like this appears in George Zebrowski's novel MACROLIFE, and Poul Anderson's novel TAU ZERO. But I digress.

There was a second, unrelated paper that suggests that aliens can live inside black holes. That is, if you have a black hole that has an electrical charge and is rotating, in its interior (inside the inner Cauchy horizon) there are stable orbits a planet can occupy. In theory, highly advanced aliens could live on such planets, being unobservable from outside while exploiting the high energies and large time dialtions available. Not to mention the delicious possibilities of causality violations. Probably a Kardashev type III civilization. A pity they cannot escape.

Of course, they can escape if they have faster-than-light starships. The "surface" of a black hole is its event horizon. This is the point where the black hole's escape velocity is equal to the speed of light. Inside, the escape velocity is faster than light. Which presumably a faster-than-light starship is capable of. This makes an appearance in the Heechee novels of Frederik Pohl.

Anyway, Adam Crowl decided to combine these two papers. Imagine black holes older than the universe, containing aliens who are obviously also older than the universe. Elder godlike beings older than time, imprisoned in other dimensions. Oh my god, it's Cthulhu.

But that's OK. They cannot escape from inside the black hole. That is, of course, until some idiot in an FTL starships travels inside just to see whats there. I guess that's "when the stars are right".

(Actually this sounds more like the Cthulhu mythos elder god Yog-Sothoth who is coterminous with all time and space yet is supposedly locked outside of the universe we inhabit.)

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