Lonely wanderer

One of the most curious unsolved problems in physics is the three-body problem, which despite its name is not about a ménage-à-trois.  It has to do with calculating the trajectory of orbits of three (or more) objects around a common center of mass, and despite many years of study, the equations it generates seem to have no general solution.

There are specific solutions for objects of a particular mass starting out with a particular set of coordinates and velocities, and lots of them result in highly unstable orbits.  But despite the fact that there are computer models that can predict the movements of three objects in a gravitational dance -- such as the members of a triple-star system -- the overarching mathematical framework has proven intractable.

How, then, can we predict the orbits of the eight planets (and countless dwarf planets, asteroids, and comets) around the Sun to such high precision?  Some of the great names of physics and astronomy in the sixteenth and seventeenth centuries -- Galileo Galilei, Tycho Brahe, Johannes Kepler, and Isaac Newton, especially -- used highly accurate data on planetary positions to conclude that the planets in the Solar System go around the Sun in elliptical orbits, all powered by the Universal Law of Gravitation.  The mathematical model they came up with worked to a high degree of accuracy, allowing earthbound astronomers to predict where the planets were in the sky, and also such phenomena as eclipses.

The reason it works, and doesn't fall prey to the three-body problem chaos, is that the Sun is so massive in comparison to the objects orbiting it.  Because the Sun is huge -- it has a thousand times more mass than the largest planet, Jupiter -- its gravitational pull is big enough that it swamps the pull the planets exert on each other.  For most purposes, you can treat each orbit as independent two-body problems; you can (for example) look at the masses, velocities, and distances between the Sun and Saturn and ignore everything else for the time being.  (Interestingly, it's the slight deviation of the orbit of Uranus from the predictions of its position using the two-body solution that led astronomers to deduce that there must be another massive planet out there pulling on it -- and in 1846 Neptune was observed for the first time, right where the deviations suggested it would be.)

I said it was "lucky" that the mass imbalance is so large, but I haven't told you how lucky.  It turns out that all you have to do is add one more object of close to the same size, and you now have the three-body problem, and the resulting orbit becomes unpredictable, chaotic, and -- very likely -- unstable.

It's what I always think about when I hear woo-woos burbling on about Nibiru, a huge extrasolar planet that has been (repeatedly) predicted to come zooming through the Solar System.  We better hope like hell this doesn't happen, and not because there could be collisions.  A huge additional mass coming near the Earth would destabilize the Earth's orbit, and could cause it to change -- very likely making it more elliptical (meaning we'd get fried at perigee and frozen at apogee).  Interestingly, this is one thing that even the writers of Lost in Space got right, at least temporarily.  The planet John Robinson et al. were on had a highly elliptical orbit, leading to wild climatic fluctuations.  The "temporarily" part, though, came about because apparently the writers found it inconvenient to have the Robinson Family deal with the alternating icebox/oven climate, and after a short but dramatic story arc where they were contending with it, it never happened again.

Or maybe the planet just decided to settle down and behave.  I dunno.

An unstable orbit can also have one other, even more dire outcome; it can cause a planet to get ejected from its star system entirely.  This would be seriously bad news if it happened here, because very quickly we'd exit the habitable zone and be frozen solid.  This is likely the origin of rogue planets -- planets that started out orbiting a star, but somehow have lost their gravitational lock, and end up floating in the vast dark of interstellar space.

This does bring up an interesting question, though; if they're out in outer space, but emit no light, how do we know they're there?  Well, they were conjectured for decades, based on the argument above, about orbital instability; but as far as detection goes, that's proven harder.  But now, we have actually detected one, and how we did it is absolutely staggering.

One of the outcomes of Einstein's General Theory of Relativity is that the presence of matter warps space.  A common two-dimensional analogy is a bowling ball sitting on a trampoline, deflecting the membrane downward.  If you roll a marble on the trampoline, it'll curve around the bowling ball, not because the bowling ball is magically attracting the marble, but because its presence has changed the shape of the space the marble is moving through.  Scale that up by one dimension, and you've got the idea.

What's cool about this is that because it's the shape of spacetime that has warped, everything passing through that region is affected -- including light.  This is called gravitational lensing, and has been used to infer the positions and masses of black holes, which (duh) are black and therefore hard to see.  But by detecting the distortion of light emitted by objects behind the black hole, we can see its effects.

And now, that's been done with a rogue exoplanet.  Judging by the lensing effect it created, it's about the mass of Saturn, and the conclusion based on its mass and velocity was that it was indeed once part of a planetary system -- and then got ejected, probably because of a close encounter with another massive object, or perhaps because it was part of a multiple star system and was in an unstable orbit from the get-go.

Now, though, it's lost -- a lonely wanderer tracking its way through the vastness of interstellar space.  How many of these rogue planets there are is unknown; as you probably concluded, detection isn't easy, relying on having a powerful telescope aimed in the right direction at the moment the planet passes in front of a distant star.  But given how easy it is to destabilize an orbit, there are likely to be millions.

Which, we have to hope, will all stay the hell away from us.  Nibiru notwithstanding, having a rogue planet pass through the Solar System would make even Donald Trump drop to number two on the List Of The Biggest Current Threats To Humanity.  Fortunately, it's unlikely; space is big.  We'd also likely have a decent amount of warning, because as soon as it got near enough (right around the orbit of Pluto), it'd reflect enough of the Sun's light that it'd become visible to astronomers.

Unfortunately, though, there's probably nothing much we could do about it.  We've just begun to experiment with the possibility of deflecting small asteroids; deflecting an entire planet, especially one the size of Saturn, would be a case where the best strategy would be to stick your head between your legs and kiss your ass goodbye.

I mean, not to end on a pessimistic note.  Let's all focus on the "unlikely" part.  And continue working on the next biggest threat, which frankly is occupying more of my anxiety at the moment.

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Ain't no sunshine

Because we evidently don't have enough to worry about, now we have news that a rogue dead star has entered our Solar System and is eating the Sun.

I'm not making this up, but the person who made the claim, one Dr. Claudia Albers, almost certainly is.  She once worked for the University of Witwatersrand, in Johannesburg, South Africa, but resigned last July for unspecified reasons.  I suspect it must have been that her department chair found out she'd gotten her Ph.D. from Big Bob's Discount Diploma Factory, but that's just a guess.

My reason for saying this is that Dr. Albers doesn't sound like a physicist, she sounds like a complete loon.  Here are her own words regarding the imminent catastrophe:

They are old or dead stars - I never said they were planets - they are stars draining the Sun of energy.  It is likely a huge system of old dead suns that have come to the Sun and been affecting it.  They are making plasma connections with the Sun and can make the Sun go dark, the Sun is getting weaker...  

These objects are causing changes in the solar system that cause earthquakes and volcanic eruptions.  Earth appears to have captured one of these objects - there are crustal displacements on Earth... 

It is not a passing system, it is in orbit around the Earth.  It is a huge system of stars attracted to the Sun and that stays close to the Sun once it is in our solar system.  I recently discovered they may have gone from the Sun to planets and that may be why Jupiter went from 16 satellites to 69, it must have captured something... 

It seems that the object is here and it is not alone because there is evidence that there are many of these objects in the inner solar system and they have been coming in towards the Sun for many years.

As you might expect, she accuses NASA of covering the whole thing up.  "If there is nothing to hide," Albers says, "then give us the real time view of the Sun – if there is nothing to hide then open it up, why do you only give us little snippets with a huge delay?"  Because clearly the only possible explanation there could be for why NASA isn't opening up all of its digital images to scrutiny is that a gigantic dead star is feeding on the Sun and they don't want you to know about it.

[image courtesy of NASA/JPL]

 Of course, the above claim brought up questions as to whether this rogue star is the same as "Nibiru," the mysterious "Planet X" that has been a favorite of woo-woos for years.  Said wingnuts have claimed over and over that Nibiru is coming, and that it's going to wreak havoc on the Earth, but then it never shows up.  Just as well.  We're wreaking enough havoc down here on our own, lately.

But Albers says that no, this isn't Nibiru.  "There is no evidence this system is the same system that came through before," she said.

At that point, I gave the computer the head-tilt of puzzlement, similar to what my dog does when I give him an unreasonable and/or unintelligible command, such as to stop eating my shoe and gnaw instead on one of his 1,385 chew toys.  What does she mean, "the same system that came through before?"  I think I'd have been aware if a humongous exoplanet had suddenly swooped down and caused massive planetary-wide destruction.  It's hard to imagine missing that.

Be that as it may, Albers says that this time it's really serious, that the rogue dead star is feeding, vampire-like, on the energy from the Sun, and pretty soon the Sun will run out and go dark, which will kind of suck.  I mean, that's what happened at the end of Star Wars Episode Number Who the Hell Can Keep Track: The Force Awakens, wherein Kylo Ren et al. turned on a machine that sucked all the energy out of a star, but instead of the planet that orbited it turning immediately into a gigantic popsicle, it was still warm enough for Kylo and Rey to leap about and get into a protracted light saber battle.

So heaven knows we don't want that.  The good news is that João A. P. Rodrigues, head of the University of Witwatersrand School of Physics, was pretty unequivocal that Dr. Albers is talking out of her ass.  He didn't put it that way, of course.  "The University supports the freedom of people to hold and discuss contrarian views," Rodrigues said.  "However, insofar as the sciences are concerned the principles of the scientific method must guide the process.  Debate outside this framework constitutes bad science and the University distances itself from such practice."

Which is academic-speak for "You're talking out of your ass."

Anyhow, I'm not worried.  I figure we have more pressing matters to worry about right now, such as how to keep Donald Trump from opening the Seventh Seal of the Apocalypse.  Although I have to admit that the Sun has seemed pretty weak and cool lately.  But that may be because I live in the famed "four-season climate" of upstate New York -- "almost winter," "winter," "still winter," and "road construction."