Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.
An ordinary, Sun-like star called Gaia20ehk -- eleven thousand light years away in the constellation Puppis -- had, up until 2016, a nearly flat energy output. This is more or less what our Sun would look like from that distance; yes, there are minor fluctuations, but (fortunately for us) it's pretty stable over short time intervals.
Then... well, here it is in Tsanidakis's words: "The star's light output was nice and flat, but starting in 2016 it had these three dips in brightness," he said. "And then, right around 2021, it went completely bonkers. I can't emphasize enough that stars like our Sun don't do that. So when we saw this one, we were like 'Hello, what's going on here?'"
The chaotic fluctuations in energy output were across the electromagnetic spectrum, but strongest in the infrared region. And stranger still, a more detailed analysis showed that the peculiar behavior was not from the star itself, but because there was -- suddenly -- a huge, irregular debris cloud surrounding it. This rock and dust eclipsed the star's light, but some of it was apparently radiating itself, accounting for the wild yo-yoing in the infrared. "The infrared light curve was the complete opposite of the visible light," Tzanidakis said. "As the visible light began to flicker and dim, the infrared light spiked. Which could mean that the material blocking the star is hot -- so hot that it's glowing in the infrared."
Tsanidakis and his team figured out that there was only one phenomenon that fit all the observations; two of Gaia20ehk's planets had collided with each other.
"It's incredible that various telescopes caught this impact in real time," Tzanidakis said. "There are only a few other planetary collisions of any kind on record, and none that bear so many similarities to the impact that created the Earth and Moon. If we can observe more moments like this elsewhere in the galaxy, it will teach us lots about the formation of our world."
Artist's rendition of the collision of the two planets in the Gaia20ehk system [Image credit: A. Tsanidakis et al.]
Tsandiakis and his colleagues are particularly interested in watching how this all plays out, because -- as he mentioned -- it is very similar to the process that is thought to have formed the Moon. The collision between the proto-Earth and a Mars-sized planet astronomers call Theia, something like 4.5 billion years ago, triggered the remelting of the entire combined mass; the energy of the collision sheared off a chunk of Theia, which collapsed into what would eventually become the Moon. Now that we've actually seen something similar happening in another star system, astronomers will be on the lookout for more events like this.
"How rare is the event that created the Earth and Moon? That question is fundamental to astrobiology," said James Davenport, senior author of the paper, which was published three days ago in Astrophysical Journal Letters. "It seems like the Moon is one of the magical ingredients that makes the Earth a good place for life. It can help shield Earth from some asteroids, it produces ocean tides and weather that allow chemistry and biology to mix globally, and it may even play a role in driving tectonic plate activity. Right now, we don't know how common these dynamics are. But if we catch more of these collisions, we'll start to figure it out."
Tsanidakis explains that while collisions are probably common in the early history of a stellar system, they can still occur in systems with stable, middle-aged stars like Gaia20ehk. Near passes by other stars, or by rogue exoplanets, could destabilize planetary orbits, causing one of the system's planets either to be ejected, or (in this case) gradually to spiral inward. This could explain the three dips in brightness that was his first clue something odd was happening -- they represent grazing passes as the two planets' orbits overlapped more and more. But eventually, they got close enough that there was a head-on impact, and all hell broke loose.
Considering the quantity of data that missions like Gaia produce, I find it astonishing that Tsanidakis and his colleagues even picked up on it. You have to wonder what other wonders might be hidden in the enormous hauls from JWST, Hubble, and (soon) the Vera Rubin Telescope. Fortunately, a sharp-eyed astronomer caught this one, and as a result we've learned a huge amount about exoplanetary collisions.
It's staggering to think about. The awe-inspiring vistas we're seeing through our best telescopes are only now being studied and analyzed, and who knows what else the astronomers will find?
All from following astrophysicist Neil deGrasse Tyson's adjuration -- "Keep looking up."
Coming right on the heels of yesterday's post about a star so large the astrophysicists are at a loss to explain how it even exists, today we have...
... a supermassive black hole moving so fast it seems to be exceeding the escape velocity of the entire galactic cluster.
The paper about the discovery, by Yale University astronomer Pieter van Dokkum et al., appeared last week in Astrophysical Journal Letters, and its findings are hard to summarize without lapsing into superlatives. Data from the James Webb Space Telescope identified a large, rapidly-moving object from its bow shock -- the compression waves surrounding a projectile as it moves through a medium (picture the pile-up of water and resulting waves preceding a boat as it moves across the surface of a lake). But an analysis of this particular bow shock demonstrated something incredible; the object creating it was ten million times the mass of the Sun -- thus, a supermassive black hole -- and it was moving at an estimated three hundred kilometers a second.
For reference, this is over two hundred times faster than the muzzle velocity of a rifle bullet.
A map of the JWST data that led to the discovery [Image credit van Dokkum et al.]
Amongst the many cool things about this discovery is that there is a higher-than-expected number of very young stars in the wake of this thing. Apparently, the compression caused by the black hole is triggering gas cloud collapse and star formation as it passes.
What could give something this massive that much momentum? The quick answer is "no one knows for sure," but a good candidate is a galactic merger. Two colliding galaxies represent a quantity known to astrophysicists as "a shitload of kinetic energy," and the slingshot effect -- where two moving objects pass close enough to each other that there's a transfer of momentum, causing one to slow down and the other to accelerate -- could be responsible. It might be that this was once the black hole at the center of a galaxy, but the collision caused it to swing around an even more massive black hole from the other galaxy, resulting in its being jettisoned -- not just from the combined mass of the merger, but from the entire galactic cluster.
The question that naturally comes up is "what if it was headed toward us?" Well, to start with, it's not; just a glance at the map of the bow shock should tell you that. Second, its light has a red shift of 0.96, putting it at about a billion light years away, so even if it was, it wouldn't be anything you or I would have to fret about in our lifetimes.
On the other hand, what if there was a black hole like this headed our way? Being black (as advertised), would we see it coming before the Earth was messily devoured? The answer is "almost certainly;" not only would there be the effects of the compression waves heating up the gas ahead of it, causing it to emit radiation, there'd be the fact that massive black holes cause gravitational lensing -- they bend and distort the light of objects behind them. If we were looking down the barrel of a black hole headed our way, we'd see this as an optical effect called an Einstein-Chwolson ring:
[Nota bene: black holes that are not moving toward us also cause gravitational lensing and Einstein-Chwolson rings; it'd be the combination of the lensing effect and the heating of the gas in front of the black hole that would tell us it was heading in our direction.]
Given astronomical distances, though, we still wouldn't have to worry about anything in our lifetimes. It might be bad news for our possible descendants a hundred million years from now, but there are way worse problems to concern ourselves with in the interim. And in any case, even if there was a supermassive black hole headed our way that was due to arrive either a hundred million years from now or a week from next Tuesday, there'd be absolutely nothing we could do about it. Altering the trajectory of a something with ten million times the mass of the Sun, traveling at three hundred kilometers per second, gives new meaning to the word "unfeasible." The only option, really, would be to stick your head between your legs and kiss your ass goodbye.
But like I said, the one van Dokkum et al. discovered isn't going to be a problem, even millions of years from now. It's something we can goggle at from a safe distance. A massive bullet flying through space, leaving a spangle of new stars in its wake. Yet another example of how endlessly awe-inspiring the universe is -- and the more we find out about it, the more wonderful it gets.
Way back around 1910, Danish astronomer Ejnar Hertzsprung and American astronomer Henry Norris Russell independently found a curious pattern when they did a scatterplot correlation between stars' luminosities and temperatures.
The graph, now called the Hertzsprung-Russell Diagram in their honor, looks like this:
Most stars fall on the bright swatch running from the hot, bright stars in the upper left to the cool, dim stars in the lower right; the overall trend for these stars is that the lower the temperature, the lower the luminosity. Stars like this are called main-sequence stars. (If you're curious, the letter designations along the top -- O, B, A, F, G, K, and M -- refer to the spectral class the star belongs to. These classifications were the invention of the brilliant astronomer Antonia Maury, whose work in spectrography revolutionized our understanding of stellar evolution.)
There is also a sizable cluster of stars off to the upper right -- relatively low temperatures but very high luminosities. These are giants and supergiants. In the other corner are white dwarfs, the exposed cores of dead stars, with very high temperatures but low luminosity, which as they gradually cool slip downward to the right and finally go dark.
So there you have it; just about every star in the universe is either a main-sequence star, in the cluster with the giants and supergiants, or in the curved streak of dwarf stars at the bottom of the diagram.
Emphasis on the words "just about."
One star that challenges what we know about how stars evolve is the bizarre Stephenson 2-18, which is in the small, dim constellation Scutum ("the shield"), between Aquila and Sagittarius. At an apparent magnitude of +15, it is only visible through a powerful telescope; it wasn't even discovered until 1990, by American astronomer Charles Bruce Stephenson, after whom it is named.
Its appearance, a dim red point of light, hides how weird this thing actually is.
When Stephenson first analyzed it, he initially thought what he was coming up with couldn't possibly be correct. For one thing, it is insanely bright, estimated at a hundred thousand times the Sun's luminosity. Only its distance (19,000 light years) and some intervening dust clouds make it look dim. Secondly, it's enormous. No, really, you have no idea how big it is. If you put Stephenson 2-18 where the Sun is, its outer edge would be somewhere near the orbit of Saturn. You, right now, would be inside the star. Ten billion Suns would fit inside Stephenson 2-18.
If a photon of light circumnavigated the surface of the Sun, it would take a bit less than fifteen seconds. To circle Stephenson 2-18 would take nine hours.
This puts Stephenson 2-18 almost off the Hertzsprung-Russell Diagram -- it's in the extreme upper right corner. In fact, it's larger than what what stellar evolution says should be possible; the current model predicts the largest stars to have radii of no more than 1,500 times that of the Sun, and this behemoth is over 2,000 times larger.
Astronomers admit that this could have a simple explanation -- it's possible that the measurements of Stephenson 2-18 are overestimates. But if not, there's something significant about stellar evolution we're not understanding.
Either way, this is one interesting object.
There's also a question about what Stephenson 2-18 will do next. Astrophysicists suspect it might be about to blow off its outer layers and turn either into a luminous blue variable or a Wolf-Rayet star (the latter are so weird and violent I wrote about them here a while back). So it may not be done astonishing us.
As far as the scientists, they love peculiar puzzles like this. Contrary to the picture many people have, of scientists being stick-in-the-mud conservatives who do nothing but prop up the current dominant paradigm, the vast majority of scientists absolutely live for having their prior notions being challenged, because that's when new avenues for understanding open up.
As the brilliant polymath Isaac Asimov put it, "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!', but '... that's funny.'"
Some of you may have heard of the Sylacauga meteorite -- a 5.5 kilogram, grapefruit-sized piece of rock that gained more notoriety than most because it crashed through a woman's roof on the afternoon of November 30, 1954, and hit her on the hip as she slept on the sofa.
The victim, Ann Hodges of Sylacauga, Alabama, was bruised but otherwise okay.
Here's Hodges with her rock, and an expression that clearly communicates, "A woman can't even take a damn nap around here without this kind of shit happening."
Hodges isn't the only one who's been way too close to falling space rocks. In August of 1992 a boy in Mbale, Uganda was hit by a small meteorite -- fortunately, it had been slowed by passing through the tree canopy, and he was startled but unharmed. Only two months later, a much larger (twelve kilogram) meteorite landed in Peekskill, New York, and clobbered a parked Chevy Malibu:
The most deadly meteorite fall in historical times, though, is a likely airburst and subsequent shower of rocks that occurred near Qingyang, in central China, in the spring of 1490. I say "likely" because there haven't been any meteorites from the incident that have survived to analyze, but a meteoritic airburst -- a "bolide" -- is the explanation that seems to fit the facts best.
Stones fell like rain in the Qingyang district. The larger ones were four to five catties [a catty is a traditional Chinese unit of mass, equal to about a half a kilogram], and the smaller ones were two to three catties. Numerous stones rained in Qingyang. Their sizes were all different. The larger ones were like goose's eggs and the smaller ones were like water-chestnuts. More than ten thousand people were struck dead. All of the people in the city fled to other places.
The magnitude of the event brings up comparisons to the colossal Tunguska airburst of 1908, when a meteorite an estimated fifty meters in diameter exploded above a (fortunately) thinly-populated region of Siberia, creating a shock wave that blew down trees radially outward for miles around, and registered on seismographs in London.
Interestingly, the Qingyang airburst wasn't the only strange astronomical event in 1490; Chinese, Korean, and Japanese astronomers also recorded the appearance of a new comet in December of that year. From their detailed records of its position, modern astronomers have calculated that its orbit is parabolic -- in other words, it won't be back, and is currently on its way out of the Solar System. However, it left a debris trail along the path of its one pass near us which is thought to be the origin of the bright Quadrantid meteor shower, which peaks in early January.
It's likely, however, that the Qingyang airburst and the December comet were unrelated events.
Much has been made of the likelihood of Earth being struck by an asteroid, especially something like the Chicxulub Impactor, which 66 million years ago ended the hegemony of the dinosaurs. Thing is, most of the bigger items in the Solar System's rock collection have been identified, tracked, and pose no imminent threat. (There is, however, a four percent chance that a seventy-meter-wide asteroid will hit the Moon in 2032, triggering a shower of debris, some of which could land on Earth.)
But there are lots of smaller rocks out there that we'd never see coming. The 2013 Chelyabinsk airburst was estimated to be from an eighteen-meter-wide meteor, and created a shock wave that blew in windows, and a fireball that was visible a hundred kilometers away. Our observational ability has improved dramatically, but eighteen meters is still below the threshold of what we could detect before it's too late.
The Double Asteroid Redirection Test (DART) Mission of 2022 showed that if we had enough time, we could theoretically run a spacecraft into an asteroid and change its orbit enough to deflect it, but for smaller meteors, we'd never spot them soon enough.
The good part of all this is that your chance of being hurt or killed by a meteorite is still way less than a lot of things we take for granted and do just about every day, like getting into a car. That last bit, though, is why people tend to over-hype the risk; we do that with stuff that's weird, things that would make the headlines of your local newspaper. (I remember seeing a talk about risk that showed a photograph of an erupting volcano, a terrorist bombing, an airplane crash, and a home in-ground swimming pool, and the question was, "Which of these is not like the others?" The answer, of course, was the swimming pool -- because statistically, it's much more likely to kill someone than any of the others.)
So it's nothing to lose sleep over. Unless you're Ann Hodges of Sylacauga, Alabama, who was just trying to take a damn nap for fuck's sake when this stupid rock came crashing through the roof and hit her, if you can believe it.
The list of confirmed exoplanets now exceeds six thousand. Considering the fact that the three main ways they're detected -- direct measure of stellar wobbles, transit photometry, and Doppler spectroscopy -- all require either that the host star be close, that the planets be massive, or that the planetary orbit be aligned just right from our perspective, or all three, it's almost certain that there are vast numbers of exoplanets going undetected.
All of which bodes well for those of us who would love for there to be extraterrestrial life out there somewhere.
On the other hand, of the exoplanets we've found, a great many of them are inhospitable to say the least, and some of them are downright bizarre. Here are a few of the weirder ones:
TrES-2b, which holds the record as the least-reflective planet yet discovered. It's darker than a charcoal briquet. This led some people to conclude that it's made of dark matter, something I dealt with here at Skeptophilia a while back. (tl:dr -- it's not.)
CoRoT-7b, one of the hottest exoplanets known. Its composition and size are thought to be fairly Earth-like, but it orbits its star so closely that it has a twenty-day orbital period and surface temperatures around 3000 C. This means that it is likely to be completely liquid, and experience rain made of molten iron and magnesium.
PSR J1719−1438, a planet orbiting a pulsar (the collapsed, rapidly rotating core of a giant star), and therefore somehow survived its host star going supernova. It has one of the fastest rates of revolution of any orbiting object known, circling in only 2.17 hours.
V1400 Centauri, a planet with rings that are two hundred times wider than the rings of Saturn. In fact, they dwarf the planet itself -- the whole thing looks a bit like a pea in the middle of a dinner plate.
BD+05 4868 Ab, in the constellation of Pegasus. Only 140 light years away, this exoplanet is orbiting so close to its parent star -- twenty times closer than Mercury is to the Sun -- that its year is only 30.5 hours long. This proximity roasts the surface, melting and then vaporizing the rock it's made of. That material is then blasted off the surface by the stellar wind, so the planet is literally evaporating, leaving a long, comet-like trail in its wake.
Today, though, we're going to look at some recent research about a planet that should be near the top of the "Weirdest Exoplanets Known" list. It's 55 Cancri Ae, the innermost of four (possibly six; two additional ones are suspected but unconfirmed) planets around the star 55 Cancri A, a K-type orange star a little over forty light years away. 55 Cancri Ae orbits its host star twice as close as Mercury does the Sun, making a complete ellipse around it in only a bit under three days. This means that like CoRoT-7b and BD+05 4868 Ab, it's crazy hot.
This is where some new research comes in. A presentation at an exoplanet conference in Groningen, Netherlands last week considered a puzzling feature of 55 Cancri Ae -- a measure of its heat output shows odd, non-cyclic fluctuations that don't seem to be in sync with its orbital period (or anything else). The fluctuations aren't small; some of them have approached a 1,000 C difference from peak to trough. They were first detected ten years ago, and physicists have been at a loss to account for the mechanism responsible.
But now, we might have an explanation -- and it's a doozy. Models developed by exoplanet astrophysicist Mohammed Farhat of the University of California - Berkeley found that the anomalous temperature surges could be explained as moving hotspots.
Which sounds pretty tame until you read Farhat's description of what this means. We're talking about a planet close in to a star not much smaller than the Sun, being whirled around at dizzying speeds. This means it's experiencing enormous tidal forces. The planet itself is so hot it's probably liquid down to its core. Result: tidal waves of lava several hundred meters high, moving at the speed of a human sprinter.
The presentation definitely got the attendees' attention. "This is right in the sweet spot of something that is interesting, novel, and potentially testable," said planetary astronomer Laura Kreidberg, of the Max Planck Institute for Astronomy. "I had this naïve idea that lava flows were too slow-moving to have an observable impact, but this new work is pointing otherwise."
The whole thing reminds me of the planet Excalbia from Star Trek, from the episode "The Savage Curtain," which was completely covered by churning seas of lava -- except for the spot made hospitable by some superpowerful aliens so Captain Kirk could have a battle involving Abraham Lincoln, Genghis Khan, and various other historical and not-so-historical figures to find out whether good was actually stronger than evil.
Put that way, I know the plot sounds pretty fucking ridiculous, but don't yell at me. I didn't write the script.
In any case, I doubt even the Excalbians would find 55 Cancri Ae hospitable. But it is fascinating. It pushes the definition of what we even consider a planet to be -- a sloshing blob of liquid rock with lava waves taller than a skyscraper. Makes me thankful for the calm, temperate climes of Earth.
I'll start today with a quote (often misquoted) from William Shakespeare -- more specifically, Hamlet, Act I, Scene 5:
Horatio:
O day and night, but this is wondrous strange!
Hamlet:
And therefore as a stranger give it welcome. There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.
Horatio and Hamlet, of course, are talking about ghosts and the supernatural, but it could equally well be applied to science. It's tempting sometimes, when reading about new scientific discoveries, for the layperson to say, "This can't possibly be true, it's too weird." But there are far too many truly bizarre theories that have been rigorously verified over and over -- quantum mechanics and the General Theory of Relativity jump to mind immediately -- to rule anything out based upon our common-sense ideas about how the universe works.
That was my reaction while watching a YouTube video about an astronomical object I'd never heard of -- Przybylski's Star, named after its discoverer, Polish-born Australian astronomer Antoni Przybylski. The video comes from astronomer David Kipping's channel Cool Worlds Lab, which looks at cutting-edge science -- and tantalizing new data about the universe we live in. (You should subscribe to it -- you won't be sorry.) Przybylski's Star is 355 light years from Earth, in the constellation of Centaurus, and is weird in so many ways that it kind of boggles the mind.
It's classified as a Type Ap star. Type A stars are young, compact, luminous, and very hot; the brightest star in the night sky, Sirius, is in this class.
Przybylski's Star rotates slowly. I mean, really slowly. Compared to the Sun, which rotates about once every 27 days, Przybylski's Star rotates once every two hundred years. Most type A stars rotate even faster than the Sun; in fact, a lot of them rotate so quickly that the light from their receding hemisphere and that from their approaching hemisphere experience enough red-shift and blue-shift (respectively) to smear out their spectral lines, making it impossible for us to tell exactly what they're made of.
You probably know that most ordinary stars are primarily composed of hydrogen, and of the bit that's not hydrogen, most of it is helium. Hydrogen is the fuel for the fusion in the core of the star, and helium is the product formed by that fusion. Late in their life, many stars undergo core collapse, in which the temperatures heat up enough to fuse helium into heavier elements like carbon and oxygen. Most of the rest of the elements on the periodic table are generated in supernovas and in neutron stars, a topic I dealt with in detail in a post I did about six years ago.
My point here is that if you look at the emission spectra of your average star, the spectral lines you see should mostly be the familiar ones from hydrogen and helium, with minuscule traces of the spectra of other elements. The heaviest element that should be reasonably abundant, even in the burned-out cores of stars, is iron -- it represents the turnaround point on the curve of binding energy, the point where fusion into heavier elements starts consuming more energy than it releases.
So elements that are low in abundance pretty much everywhere, such as the aptly-named rare earth elements (known to chemists as the lanthanides), should be so uncommon as to be effectively undetectable. Short-lived radioactive elements like thorium and radium shouldn't be there at all, because they don't form in the core of your ordinary star, and therefore any traces present had to have formed prior to the star in question's formation -- almost always, enough time that they should have long since decayed away.
The composition of Przybylski's Star, on the other hand, is so skewed toward heavy elements that it elicits more in the way of frustrated shrugs than it does in viable models that could account for it. It's ridiculously high in lanthanides like cerium, dysprosium, europium, and gadolinium -- not elements you hear about on a daily basis. There's more praseodymium in the spectrum of its upper atmosphere than there is iron. Even stranger is the presence of very short-lived radioactive elements such as plutonium -- and actinium, americium, and neptunium, elements for which we don't even know a naturally-occuring nuclide synthesis pathway capable of creating them.
So where did they come from?
"What we’d like to know... is how the heavy elements observed here have come about," said astronomy blogger Paul Gilster. "A neutron star is one solution, a companion object whose outflow of particles could create heavy elements in Przybylski’s Star, and keep them replenished. The solution seems to work theoretically, but no neutron star is found anywhere near the star."
"[T]hat star doesn’t just have weird abundance patterns; it has apparently impossible abundance patterns," said Pennsylvania State University astrophysicist Jason Wright, in his wonderful blog AstroWright. "In 2008 Gopka et al. reported the identification of short-lived actinides in the spectrum. This means radioactive elements with half-lives on the order of thousands of years (or in the case of actinium, decades) are in the atmosphere... The only way that could be true is if these products of nuclear reactions are being replenished on that timescale, which means… what exactly? What sorts of nuclear reactions could be going on near the surface of this star?"
All the explanations I've seen require so many ad-hoc assumptions that they're complete non-starters. One possibility astrophysicists have floated is that the replenishment is because it was massively enriched by a nearby supernova, and not just with familiar heavy elements like gold and uranium, but with superheavy elements that thus far, we've only seen produced in high-energy particle accelerators -- elements like flerovium (atomic number 114) and oganesson (atomic number 118). These elements are so unstable that they have half-lives measured in fractions of a second, but it's theorized that certain isotopes might exist in an island of stability, where they have much longer lives, long enough to build up in a star's atmosphere and then decay into the lighter, but still rare, elements seen in Przybylski's Star.
There are several problems with this idea, the first being that every attempt to find where the island of stability lies hasn't succeeded. Physicists thought that flerovium might have the "magic number" of protons and neutrons to make it more stable, but a paper released not long ago seems to dash that hope.
The second, and worse, problem is that there's no supernova remnant anywhere near Przybylski's Star.
The third, and worst, problem is that it's hard to imagine any natural process, supernova-related or not, that could produce the enormous quantity of superheavy elements required to account for the amount of lanthanides and actinides found in this star's upper atmosphere.
Which brings me to the wildest speculation about the weird abundances of heavy elements. You'll never guess who's responsible.
Go ahead, guess.
There is a serious suggestion out there -- and David Kipping does take it seriously -- that an advanced technological civilization might have struck on the solution for nuclear waste of dumping it into the nearest star. This explanation (called "salting"), bizarre as it sounds, would explain not only why the elements are there, but why they're way more concentrated in the upper atmosphere of the star than in the core.
"Here on Earth... people sometimes propose to dispose of our nuclear waste by throwing it into the Sun,” Wright writes. “Seven years before Superman thought of the idea, Whitmire & Wright (not me, I was only 3 in 1980) proposed that alien civilizations might use their stars as depositories for their fissile waste. They even pointed out that the most likely stars we would find such pollution in would be… [type] A stars! (And not just any A stars, late A stars, which is what Przybylski’s Star is). In fact, back in 1966, Sagan and Shklovskii in their book Intelligent Life in the Universe proposed aliens might 'salt' their stars with obviously artificial elements to attract attention."
A curious side note is that I've met (Daniel) Whitmire, of Whitmire & Wright -- he was a professor in the physics department of the University of Louisiana when I was an undergraduate, and I took a couple of classes with him (including Astronomy). He was known for his outside-of-the-box ideas, including that a Jupiter-sized planet beyond the orbit of Pluto was responsible for disturbing the Oort Cloud as it passed through every hundred million years or so (being so far out, it would have a super-long rate of revolution). This would cause comets, asteroids, and other debris to rain in on the inner Solar System, resulting in a higher rate of impacts with the Earth -- and explaining the odd cyclic nature of mass extinctions.
So I'm not all that surprised about Whitmire's suggestion, although it bears mention that he was talking about the concept in the purely theoretical sense; the weird spectrum of Przybylski's Star was discovered after Whitmire & Wright's paper on the topic.
Curiouser and curiouser.
So we're left with a mystery. The "it's aliens" explanation is hardly going to be accepted by the scientific establishment without a hell of a lot more evidence, and thus far, there is none. The problem is, the peculiar abundance of heavy elements in this very odd star remains unaccounted for by any science we currently understand. The fact that Kipping (and others) are saying "we can't rule out the alien salting hypothesis" is very, very significant.
I'll end with another quote, this one from eminent biologist J. B. S. Haldane: "The universe is not only queerer than we imagine, it is queerer than we can imagine."
Today I'm going to focus on outer space, because if I don't I'll be forced to deal with events down here on Earth, and it's a little early to start drinking.
The James Webb Space Telescope just posted information on a structure called the Saraswati Supercluster, which at a diameter of 650 million light years and a mass of twenty quadrillion times the mass of the Sun, is one of the largest gravitationally-bound structures known. If you look toward the constellation Pisces, visible in the Northern Hemisphere from August to early January, you're staring right at the Saraswati Supercluster.
Not that you can see it with the naked eye. Its center is about four billion light years away, meaning not only that it's extremely faint, the light from it has taken about a third of the age of the universe to get here, so it's really red-shifted. Here's the rather mind-blowing image the JWST team just posted on their site:
On this diagram, the Sun and Solar System are at the center, and as you move outward the scale increases exponentially, allowing us to visualize -- or at least imagine -- the astonishing vastness of the universe. (Saraswati is just slightly to the left of top center on the diagram.)
The name of the supercluster is from a Sanskrit word meaning "ever-flowing stream with many pools," which is appropriate. It's made of forty-three galaxy clusters -- not galaxies, mind you, but galaxy clusters -- of which the largest, Abell 2631, is thought to be made up of over a thousand galaxies (and something on the order of a hundred trillion stars).
If your mind is not boggling yet, you're made of sterner stuff than I am.
Because of its distance and faintness, we haven't known about Saraswati for all that long. It was discovered in 2017 by a team of Indian astronomers led by Joydeep Bagchi from the Inter-University Centre for Astronomy and Astrophysics (IUCAA) in Pune, India, and since has been the object of intense study by astrophysicists for two main reasons. First -- although it's phenomenally massive, its vast diameter makes it remarkable that it hangs together gravitationally. (Remember that gravitational attraction falls off as the square of the distance; it never goes to zero, but it does get really weak.) The fact that it does seem to be acting as a single structure could give us valuable information about the role of the elusive dark matter in making large objects stick together over time.
Second, it might provide some insight into solving another mystery, the question of how (or if) dark energy, the strange force that seems to be making the expansion of the universe speed up, is changing over time. You may recall that just this past August, a pair of papers came out suggesting that the strength of this peculiar phenomenon might be decreasing; that instead of heading toward the rather ghastly prospect of a "Big Rip," where dark energy overpowers every other known force and tears matter apart into a soup of subatomic particles, the expansion might eventually stop or even reverse. The old "oscillating universe" idea, that the universe goes through an endless series of expansions and collapses -- popularized by such brilliant luminaries of physics as Paul Steinhardt and Roger Penrose -- might have legs after all. Studying Saraswati might give us more information about how the strength of dark energy has changed in the four-billion-odd years it's taken the light from the supercluster to arrive here.
So next time you look up into a clear night sky, think of what lies beyond the bit you can actually see. Every individual star visible to the naked eye lives in a (relatively) tiny sphere in the Orion Arm of the Milky Way. The few bits that visible but are farther away -- the smear of light that is all we can discern of the rest of our own galaxy, as well as the few other galaxies we can see without a telescope (like Andromeda and the two Magellanic Clouds) are so distant that individual stars can't be resolved without magnification. What we think of as the impressive grandeur of the night sky is, basically, like thinking you're a world traveler because you drove around your own neighborhood once or twice.
But I guess I need to come back down to Earth. Unfortunately. On the whole, I'm much happier looking up. It makes the current horror show we're living through at least seem a little less overwhelming, and puts our own place in the universe into perspective.
Maybe if our so-called leaders spent more time stargazing, it might provide them with some much-needed humility.
Okay, can we all please please puhleeeeeez stop posting stuff without checking to see if it's true?
I know it's a pain in the ass, but this needs to become a habit. For all of us. Unless you make a practice of never reposting anything anywhere -- which eliminates most people -- it's got to become an automatic reflex when you're using social media. Stop before you hit "forward" or "share" or whatnot and take five minutes to verify that it's accurate.
The reason this comes up is something about comet 3I-ATLAS that I've now seen posted four times. I wrote about 3I-ATLAS here only a couple of weeks ago, and to cut to the chase: the considered opinions of the astronomers who have studied it -- i.e., the people who actually know what the hell they're talking about -- are that the object is an interstellar comet made mostly of frozen carbon dioxide. Despite the claims of people like Avi Loeb, the alien-happy Harvard astronomer, it shows no sign of being an extraterrestrial spacecraft.
That, of course, isn't sufficient for a lot of people. Without further ado, here's the image I've seen repeatedly posted:
There is nothing in this image that is accurate, unless you're counting "3I-ATLAS is an interstellar object" and "Japan has a space agency" as being in the "correct" column. Japan's space agency has released no such "footage." There are no "precise pulsating lights." No scientist -- again, with the exception of Loeb and his pals -- are "questioning if it's artificial."
And the object in the image? That's not 3I-ATLAS. Jack Gilbert, of the Scripps Institute of Oceanography, has identified it as a microorganism. "That is a paramecium," Gilbert writes. "Freshwater I believe -- although better phase contrast, and where it was found, would be ideal for better identification."
Another image that is making the rounds is from NASA, but it's being used to claim that the 3I-ATLAS has changed direction and speed in a fashion that "indicates some kind of propulsion system." This shift in trajectory, they say, made the telescope at NOIRLab (National Optical-Infrared Astronomy Research Laboratory) image alter its aim to keep up with it, resulting in the background stars showing rainbow-colored streaks:
This isn't correct, either. If you go to NOIRLab's website, you find a perfectly reasonable explanation of the streaks right there, without any reference to propulsion systems and alien spacecraft. I quote:
Comet 3I/ATLAS streaks across a dense star field in this image captured by the Gemini Multi-Object Spectrograph (GMOS) on Gemini South at Cerro Pachón in Chile, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab. This image is composed of exposures taken through four filters -- red, green, blue and ultraviolet. As exposures are taken, the comet remains fixed in the center of the telescope's field of view. However, the positions of the background stars change relative to the comet, causing them to appear as colorful streaks in the final image.
Once again, the upshot: 3I-ATLAS is a comet. That's all. Of great interest to planetary astronomers, but likely to be forgotten by just about everyone else after March of next year, at which point it will be zooming past Jupiter and heading back out into the depths of space, never to be seen again. There is no credible evidence it's a spaceship. If there was, believe me, you would not be able to get the astronomers to shut up about it. The concept some people have of scientists keeping stuff hidden because they're just that secretive, and don't want anyone to know about their big discoveries, only indicates to me that these people know exactly zero scientists. Trust me on this. I know some actual scientists, and every single one of them loves nothing better than telling you at length about what they're working on, even if it's something that would interest 0.00000001% of the humans who have ever lived, such as the mating habits of trench-dwelling tube worms. If there was strong (or, honestly, any) observation that supported this thing being the ship from Rendezvous With Rama, we'd all know about it.
And after all, if there was evidence out there, the hoaxers wouldn't have to use a photograph of a paramecium to support their bogus claims.
So for fuck's sake, please be careful about what you post. It took me (literally) thirty seconds to find a site debunking the "Japan space agency" thing. What I'm asking you to do is usually not in any way onerous.
I mean, really; wouldn't you rather be posting things that are cool, and also true? There is so much real science to be fascinated and astonished by, you don't need these crazy claims.
And believe me, neither does the internet as a whole.
A loyal reader of Skeptophilia sent me an email asking me what my opinion was about two current candidates for evidence of alien spacecraft -- the Palomar transients and the object called 3I-ATLAS.
First, some facts.
The Palomar transients are some mysterious moving objects spotted on photographic plates taken at Palomar Observatory in the 1940s and 1950s, all before the launch of Sputnik 1, the first artificial satellite, in 1957. They included both single objects and multiple objects -- in one case, five -- arrayed in a straight line. In-depth analysis ruled out conventional explanations like meteors and flaws in the photographic plates; and curiously, there was a forty-five percent higher likelihood of transient detection within one day of nuclear testing, which was going on pretty regularly at the time. The transients also were a little over eight percent more likely on days when there were UAP reports from other sources -- either visual observation by pilots or on-ground observers, or unexplained blips on military radar. The authors of the paper, which appeared in Nature last week, were up front that the phenomenon was "not easily accounted for by prosaic explanations."
One of the Palomar transients, from July 1952 [Image courtesy of Stephen Bruel and Beatriz Villarroel, Nature, 20 October 2025]
3I-ATLAS is an interstellar object -- that's what the "I" stands for. (The ATLAS part is because it was discovered by the Asteroid Terrestrial-impact Last Alert System; but fear not, the closest it will get to Earth is 1.8 astronomical units, so it poses no impact threat.) We know it's an unbound interstellar object because of its speed and trajectory. It's on a hyperbolic path, having come from somewhere in deep space, falling into the gravity well of the Sun, where it will ultimately slingshot its way back out of the Solar System and into deep space once again. From analyses of the object itself, as well as the gas and dust it is currently ejecting, it appears to be an icy comet something on the order of three kilometers across, and mostly composed of frozen carbon dioxide, with small amounts of water ice, carbon monoxide, and carbonyl sulfide.
Comet 3I-ATLAS [Image licensed under the Creative Commons International Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist, 3I-ATLAS noirlab2525b crop, CC BY 4.0]
3I-ATLAS was immediately grabbed by (now rather notorious) astronomer Avi Loeb, whose unfortunate habit of shouting "IT'S ALIENS!" every time something unexplained happens has brought up repeated comparisons to The Boy Who Cried Wolf. Not long after 3I-ATLAS was confirmed to be an interstellar object, Loeb and a couple of collaborators published a paper on arXiv in which they said its "anomalous characteristics" indicate it's an extraterrestrial spacecraft, and might in fact be hostile. The claim was equally quickly shot down by a large number of exasperated astrophysicists who are sick unto death of Loeb's antics. One, Samantha Lawler, said, "while it is important to remain open-minded about any 'testable prediction', the new paper [by Loeb et al.] pushes this sentiment to the limit... [E]xtraordinary claims require extraordinary evidence, but unfortunately, the evidence presented is absolutely not extraordinary."
What strikes me here -- especially with regards to the (many) folks who have weighed in on the possibility that these are evidence of extraterrestrial intelligence -- is the need for a rush to judgment. (Nota bene: this is in no way meant as a criticism of the reader who contacted me with the question; she was just interested in my take both on the facts of the case, and people's reactions to them.) In the case of 3I-ATLAS, I think the evidence very strongly suggests that what we have here is simply a large comet of interstellar origin, so something of great interest to astronomers and astrophysicists, but unlikely otherwise to be earthshattering in any sense including the literal one. As far as the Palomar transients go -- well, we don't know. The most recent of them occurred seventy-odd years ago, and all we have is some old photographic plates to go by. They're certainly curious, and I'm glad they're being looked at, but... that's about all we can say for the time being.
"Well, what about the Menzel Gap?" I've seen asked multiple times. Isn't that suggestive? The "Menzel Gap" refers to the fifteen-year block of missing plates attributable to actions by Harvard Observatory astronomer Donald Howard Menzel, a prominent scoffer about aliens and UFOs, who became notorious for ordering the destruction of hundreds, possibly thousands, of astronomical photographic plates stored there. Menzel cited considerations of storage space, claiming we'd already learned as much from them as we could, but UFO aficionados hint at something darker. Menzel had top secret security clearance, they say; he led a "clandestine life as an elite member of the U. S. intelligence community" and was systematically covering up evidence of aliens visiting the Earth in the fashion of Cigarette-Smoking Man on The X Files.
Why he and others would go to all that trouble to stop the public from finding out about aliens is never really explained. "They were just that evil" is about the clearest it gets, often along with vague claims that it was to prevent panic amongst the populace.
As if what the government was openly doing at the time, and that made headlines worldwide, wasn't equally bad.
In any case, back to the original question: what do I think about all this?
Well, the truth is, I don't think anything. I simply don't know. It seems likely that whatever the Palomar transients were, they were not all due to the same cause; it could be that some were debris from nuclear testing, but that clearly doesn't account for all of them. Menzel might have been a misguided bureaucrat, or might have been destroying the plates to prevent their being co-opted by the UFOs-and-aliens crowd, or may have had some other motives entirely. In any case, it's okay to say "we don't know," and then just leave it there. Perhaps researchers will find more evidence, perhaps not; in either case, the best thing is to hold the question in abeyance, indefinitely if need be.
So that's where we have to leave it. I know that's disappointing; believe me, I've been waiting since I was a six-year-old breathlessly watching Lost in Space for unequivocal evidence of aliens. At the moment, what we've got simply doesn't amount to much. But if you're as intrigued by the possibilities as I am, I have two suggestions.
First, learn some actual astronomy and astrophysics. You're less likely to fall for specious claims if you have a good command of the facts and current scientific models.
Second, keep looking up. As has been commented many times, "It's never aliens... until it is." I still think it's likely that life is common in the universe, and although the distances and scale (and the Einsteinian Cosmic Speed Limit) make it unlikely they've come here, it's not impossible. Maybe there have been extraterrestrial spacecraft passing by, or even landing on, our planet.
Wouldn't it be fun if you were the first to know? Make sure and take lots of pictures, okay?
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