Is Planet Nine a Black Hole? (nytimes.com) 105
"Astrophysicists have recently begun hatching plans to find out just how weird Planet Nine might be," reports the New York Times. Long-time Slashdot reader fahrbot-bot shares their report:
Although it is probably wishful thinking, some astronomers contend that a black hole may be lurking in the outer reaches of our solar system. All summer, they have been arguing over how to find it, if indeed it is there, and what to do about it, proposing plans that are only halfway out of this world...
Earlier this year, Edward Witten, a theoretical physicist at the Institute for Advanced Study in Princeton, chimed in... Dr. Witten suggested borrowing a trick from Breakthrough Starshot, the proposal by Russian philanthropist Yuri Milner and Dr. Hawking to send thousands of laser-propelled microscopic probes to the nearest star system, Alpha Centauri. Dr. Witten suggested sending hundreds of similarly small probes outward in all directions to explore the solar system. By keeping track of incoming signals from the probes, scientists on Earth would be able to tell if and when each one sped up or slowed down as it encountered the gravitational field of Planet Nine or anything else out there.
Key to this plan would be the ability of the probes to keep pinging Earth precisely every hundred-thousandth of a second. In May, astronomers Scott Lawrence and Zeeve Rogoszinski of the University of Maryland suggested instead monitoring the trajectories of the probes with high-resolution radio telescopes, which would obviate the need for high-precision clocks on the probes.
Another idea came from Avi Loeb, chair of the astronomy department at Harvard and leader of a scientific advisory board for Breakthrough Starshot: in July Dr. Loeb was back, with a student, Amir Siraj, and a new idea for finding the Planet Nine black hole. If a black hole were out there, they argued, it would occasionally rip apart small comets, causing bright flares that could soon be spotted by the new Vera C. Rubin Observatory, previously known as the Large Synoptic Survey Telescope, now under construction in Chile. The observatory's mission, starting in 2021, is to make a movie of the universe, producing a panorama of the entire southern night sky every few days and revealing anything that has changed or moved. Such flares should occur a few times a year, they noted. "Our calculations show that the flares will be bright enough for the Vera Rubin Observatory to rule out or confirm Planet Nine as a black hole within one year of monitoring the sky with its L.S.S.T. survey," Dr. Loeb wrote in an email.
Moreover, because the Rubin telescope examines such a large swath of sky, it could detect or rule out black holes of similar size all the way out to the Oort cloud, a vague and diffuse assemblage of protocomets and primordial, frozen riffraff a trillion miles from the sun, they said.
The prospect of finding a black hole in our own solar system "is as startling as finding evidence that someone might be living in the shed in your backyard," Dr. Loeb said in the email. "If so, who is it, and how did it get there?"
Earlier this year, Edward Witten, a theoretical physicist at the Institute for Advanced Study in Princeton, chimed in... Dr. Witten suggested borrowing a trick from Breakthrough Starshot, the proposal by Russian philanthropist Yuri Milner and Dr. Hawking to send thousands of laser-propelled microscopic probes to the nearest star system, Alpha Centauri. Dr. Witten suggested sending hundreds of similarly small probes outward in all directions to explore the solar system. By keeping track of incoming signals from the probes, scientists on Earth would be able to tell if and when each one sped up or slowed down as it encountered the gravitational field of Planet Nine or anything else out there.
Key to this plan would be the ability of the probes to keep pinging Earth precisely every hundred-thousandth of a second. In May, astronomers Scott Lawrence and Zeeve Rogoszinski of the University of Maryland suggested instead monitoring the trajectories of the probes with high-resolution radio telescopes, which would obviate the need for high-precision clocks on the probes.
Another idea came from Avi Loeb, chair of the astronomy department at Harvard and leader of a scientific advisory board for Breakthrough Starshot: in July Dr. Loeb was back, with a student, Amir Siraj, and a new idea for finding the Planet Nine black hole. If a black hole were out there, they argued, it would occasionally rip apart small comets, causing bright flares that could soon be spotted by the new Vera C. Rubin Observatory, previously known as the Large Synoptic Survey Telescope, now under construction in Chile. The observatory's mission, starting in 2021, is to make a movie of the universe, producing a panorama of the entire southern night sky every few days and revealing anything that has changed or moved. Such flares should occur a few times a year, they noted. "Our calculations show that the flares will be bright enough for the Vera Rubin Observatory to rule out or confirm Planet Nine as a black hole within one year of monitoring the sky with its L.S.S.T. survey," Dr. Loeb wrote in an email.
Moreover, because the Rubin telescope examines such a large swath of sky, it could detect or rule out black holes of similar size all the way out to the Oort cloud, a vague and diffuse assemblage of protocomets and primordial, frozen riffraff a trillion miles from the sun, they said.
The prospect of finding a black hole in our own solar system "is as startling as finding evidence that someone might be living in the shed in your backyard," Dr. Loeb said in the email. "If so, who is it, and how did it get there?"
Where are we going?! (Score:4, Funny)
When?
Real soon now!
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Hey, it's not my planet, monkey-boy.
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I gotta go with no planet. At a guess planet 9 is a dust cloud with a heavy core, the left overs of the impact upon Venus, got it to turn in the opposite direction and hugely altered it's orbit. There is no where it get generate a large enough impact to alter rotation with out also altering it's orbit a lot and of course throwing a large chunk of it off into space. So I kinda like Mars as a Moon or Venus and then Venus go a huge whack, a lot of it's surface ending up on it's moon mars and Venus went into a
Re:Where are we going?! (Score:5, Informative)
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No it is Ceres. Discovered before Pluto and if we're going to call every chunk of rock/ice orbiting the Sun a planet, well it was discovered earlier along with planets 10 (Pallas), 11 (Juno) and 12 (Vesta) at least. Pluto could be Planet 13 if we stopped counting those planets between Mars and Jupiter at Vesta.
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Re: Where are we going?! (Score:1)
WTF is this garbage?
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planet 10!
Personally, I'm hoping it goes up to 11 [wikipedia.org].
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Personally, I'm hoping it goes up to 11 [wikipedia.org].
If you feel that you have to link to your punch line or people won't get it then maybe it's time for the joke to be retired.
Déjà vu! (Score:2)
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Pluto (Score:5, Funny)
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I can't wait for 2620...
Re:Pluto (Score:5, Funny)
Re:Pluto (Score:4, Funny)
NO! Nicht! Verboten! Pluto is out! And next, we're kicking fucking Plutonium out of the Periodic Table of Elements! And then, we're coming for Mickey Mouse's fucking dog!
I get it why they kicked Pluto out of the planet club, but out of the periodic table and Disney stories? That's just fucking goofy.
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Dwarf planet seems kinda bad language for 2020 anyway...
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Re: Pluto (Score:4, Insightful)
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Eris. Spherical and has more mass than Pluto.
You know Eris, the discovery of which is what started the process of Pluto being demoted.
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Agree on "clearing its orbit". If Pluto isn't a planet for that reason, then neither is Neptune, because it hasn't cleared its orbit of Pluto and all sorts of other objects. By that criteria, Earth isn't a planet either.
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Ceres, which also was originally classified as a Planet (for 50 years) and was where a planet was expected according to Bole. Of course as it was discovered before Neptune, it would have been Planet 8 by discovery or Planet 5 in order of distance from the Sun.
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Are you at least going to propose to add everything else that size into the count?
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Wouldn't it have to be small? (Score:2)
Re: Wouldn't it have to be small? (Score:3)
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As in, say, a microsingularity? They've already been raising the possibiity of that, as I recall.
It's gravitational reach would be relatively small as well, as opposed to a 'normal' black hole, am I right?
Re: Wouldn't it have to be small? (Score:4, Informative)
If it were planet-mass, it's gravitational reach and power would be exactly the same as a planet of the same mass.
The gravitational differences between a black hole and a larger, less-dense object of the same mass begin roughly at the point where you'd crash into the surface of the less-dense object. Though outside that range there there'd be some relatively subtle tidal differences as well.
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Yes, but their simulations have already said it should be somewhere around 8 Earth masses (they've bounced around from 5-15, but I think 8 is the latest).
Re: Wouldn't it have to be small? (Score:2)
Aren't black holes started by the supernova of stars or the collapse of neutron stars? Therefore it's mass would be incredible and be far greater than 8 Earth's.
Unless it's much further away and yet more massively. At this point I would think all our planets would have a more elliptical orbit towards this black hole even if it were far away which is how the theory of this started.
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There may be other ways that black holes are created. One hypothesis is in the big bang or very shortly after, black holes of all sizes were created. So far none have been found and some hypothesis's predict that they would evaporate, the smaller, the quicker, due to quantum.
Personally, I think that even if they exist, the odds of one being captured by our Sun is pretty small. A planet sized chunk of rock is much more likely.
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> that would make it very difficult to find, despite being the largest thing (by mass) in our solar system.
I told my girlfriend the same thing... she wasn't buying it.
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Are we sure it doesn't? As I recall, most of the orbits proposed for Planet 9/X would give it an orbital period of at least thousands of years, potentially tens of thousands. And if a black hole were stellar-mass rather than planet-mass (presumably a primoridal BH) it'd have to be even further away to avoid obviously disrupting the orbits of the known planets. Have we measured the path of the sun precisely enough, for a long enough time period, that any orbital perturbations would be apparent?
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No. Jupiter has much more mass than Planet Nine is hypothesized to have. There are some unexplained things with the Sun that Planet Nine could have caused, but nothing like that.
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Further, if it were in the Oort Cloud, this would create a difference in comet speeds and trajectories considering its been there for billions of years.
The fact that pluto and many other Oort Cloud objects have such wild orbits is exactly the primary evidence for Planet 9. There is something very large and very far out that has been grabbing rocks and throwing them into wild orbits. It could also be the reason why the the Oort cloud hasn't collapsed into a planet itself, like Jupiter with the asteroid belt.
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Could not a close encounter with a star explain the orbits? A Sun sized star, or close to it, passing slowly at less then a light year might have quite an affect.
Comment removed (Score:5, Informative)
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Thanks for pointing out the article, I should read that so I have better information. To-date all I've known is what I've read in news stories, and that's not much.
Except for dropping comets on us now and then. (Score:2)
even if it'd have to have been there for billions of years and apparently not any sort of actual threat to us here on Earth..
Except for dropping comets on us now and then, by altering the orbit of an Oort cloud (or other) object that passes nearby so it falls "into the malestrom" (to quote Lucifer's Hammer) and maybe happens to hit Earth and do stuff like kill off all the dinosaurs except the birds.
It doesn't really matter if "Nemesis" is a gas giant/infrared dwarf or a black hole.
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Passing stars could have the same affect. It's not that unlikely that a star could pass by at less then a light year distance and the bigger and slower it passes, more of an affect.
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Passing stars could have the same [e]ffect. It's not that unlikely that a star could pass by at less then a light year distance and the bigger and slower it passes, more of an [e]ffect.
But stars are farther out and pass far less often. Something of gas-giant mass, close enough to orbit the sun, would be disturbing the orbits of Oort cloud objects a lot more often.
Also: To drop them into the inner solar system your disturbance has to just about zero out the components of their motion at right angles to the
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Less likely but over 4.5 billion years? We've circled the galaxy 20 times, lots of opportunity for a star to pass close enough and slow enough to have those affects.
A gas giant mass might be more likely, but not that much more likely.
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A black hole with a mass equivalent to a planet is only as dangerous as another planet. It's gravitational effect is roughly the same, and in order to swallow anything it has to collide with it. For collision with small masses like comets, the outcome would be the same if it were a regular planet. For planetary scale collisions, either scenario would be pretty catastrophic.
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A small dense planetary body, but not a 'primordial black hole', looks to be the most plausible explanation, assuming it exists at all. But of course 'black hole' looks better in a news story. xD
Seems to me if it was a black hole of any size, there'd be Hawking Radiation, and we should be able to detect that, yes? Much easier than trying to find it visually,
Re: Wouldn't it have to be small? (Score:3, Informative)
Seems to me if it was a black hole of any size, there'd be Hawking Radiation, and we should be able to detect that, yes?
From what I've read on the subject, no. Hawking radiation isn't particularly detectable unless you're right on top of the thing.
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Hawking radiation isn't particularly detectable unless you're right on top of the thing.
Nope. Hawking radiation is not detectable AT ALL. Unless the black hole is microscopic, the Hawking radiation is going to be billions of times weaker than the 4 Kelvin background radiation of the universe.
Radiation from interstellar gas falling into the BH will exceed Hawking radiation going out by many quadrillion-fold.
Re:Wouldn't it have to be small? (Score:5, Informative)
Seems to me if it was a black hole of any size, there'd be Hawking Radiation, and we should be able to detect that, yes?
The Hawking radiation "temperature" of a black hole large enough to cause these gravitational effects is currently lower than that of the cosmic background radiation. Therefore, it would not be detectable by its Hawking radiation until far in the future when the cosmic background has more redshift. Even then, it would be a tiny object just a fraction of a degree above absolute zero, so such detection would be extremely hard.
Re:Wouldn't it have to be small? (Score:4, Interesting)
The thing is, a black hole with the mass of a planet is a bit hard to explain. How do you build it? I think It would pretty much need to be a primordial black hole, but then why didn't we detect the ones slightly lighter evaporating? I even have a hard time imagining how to build one on purpose. If you try to start with a micro-black hole it's capture cross-section is too small to catch anything. You might be able to grow it by feeding it on pure neutronium, of course...
OK, this might work. You start with a micro-black hole that's primordial, and give it an orbit though (within) a closed globular cluster. Eventually it grows enough to be captured by a white dwarf, and ends up orbiting just at the surface. The dwarf is part of a binary, that is dropping hydrogen onto the white dwarf. Eventually it explodes in a supernova, and the intense pressure feeds the black hole enough to allow it to grow, while giving it enough momentum to allow it to escape.
I wouldn't know how to do the math to test that theory, but it might work. There's still the problem of not detecting primordial black holes evaporating, but maybe most of them did that before we were around to notice them. OTOH, it would make encountering one extremely unlikely...unless you can come up with a story that explains why it's presence is necessary for us to evolve here.
In other words, I consider a planetary mass black hole to be quite unlikely. More likely a failed brown dwarf, or an planet with a carbon (i.e. coal black) surface. Possibly a binary pair in orbit around each other, so they could lose heat faster, and be less detectable in infrared.
Re:Wouldn't it have to be small? (Score:4, Interesting)
Are planet mass primordial black holes ruled out? I guess they have to form post-inflation or their density would be too low, but I've seen (but can't follow) papers suggesting that it might be possible to form them at the end of inflation. I don't know the observational limits. I suspect a planetary mass black hole would blow up a neutron star in a spectacular way. Not clear if it would impact a normal star, or mostly pass through before it acquired an interesting amount of mass. A white dwarf is intermediate - at some size I guess the black hole would cause a white dwarf to supernova.
It might not be insanely unlikely for there to be one in the solar system.
It would be absolutely fantastic for science if there were - but it seems a long shot.
Re:Wouldn't it have to be small? (Score:4, Informative)
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exploration probes (Score:5, Interesting)
Re: exploration probes (Score:3)
The probe part does seem like a good idea. Bound to be great for general astronomy, lots of useful stuff.
Also, in terms of gravitational mapping, it could indicate if lumps of dark matter are present in the outer solar system, and that would be an interesting result.
Maybe (Score:2)
But then it could also be the tooth fairy's wagon. She has a wagon right?
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No, she has butterfly wings.
It is probably just CowboyNeal riding in a wagon of grits.
Wishful thinking? (Score:1)
My first thought was, why would anyone want a black hole nearby?
However, I can see how physicists would love to have a black hole within reach. Send a probe to dive in and record what happens.
How dangerous would it be? What are the chances of its orbit destabilizing, the way comet orbits occasionally destabilize, and it plunges into the inner solar system? Suppose it fell into the Sun? Would it devour the whole Sun even if it had a relatively small mass right away or would it plow through, come out the
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Garbage Disposal!!!!!
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Easiest is to dump garbage on the nearest planet, Earth.
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Also, it's a lot easier to hit. A planet-mass black hole is going to be so small that you'd basically have to fire something directly at its center of mass to hit it, anything else would tend to slingshot past it on a highly elliptical orbit, possibly being torn apart into a gaseous cloud if it passes close enough.
Why would you want a black hole? (Score:4, Insightful)
Two uses of a black hole immediately come to mind
1) It would make a *wonderful* lens for a gravitational telescope. It's disc is so small that you could orbit it at close range and sweep your view across the universe, unlike using our sun as a lens, for which the telescope has to be over 600AU away, which means its orbit lasts tens of thousands of years so it's pretty much limited to looking at one tiny section of sky over the course of a human lifetime.
2) Power. A black hole can theoretically be harnessed as a roughly 50% efficient mass-energy converter using relatively simple technology. If we came up with a use for lots of power that far away from the sun, it would make fusion reactors look like so many birthday-cake candles n comparison, while being able to use literally anything as fuel.
As for the danger - there's not really any. The difference between a black hole and a planet of the same mass starts at about the point where you'd hit the surface of the planet. And since hitting the planet would be lethal anyway, a black hole presents no additional threat. Well, except possibly as an invisible navigation hazard, but you could put some warning beacons in orbit to solve that problem.
Messed up (Score:5, Interesting)
Occasionally rip apart small comets? (Score:2)
The kiknds of densities at the Big Bang could have generated quite small black holes, but the smaller, the more quickly they evaporate due to quantum pecularities at the "horizon" of the hole. And since then, black holes could be formed from aggregating mass and condensing it. but there is a trade-off. The larger the mass, the less outrageous the density has to be. A large enough star could leave a remnant after its inevitable supernova and collapse that forms a black hole. A large enough neutron star afte
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"For stellar mass black holes, it might take 10^67 years to evaporate completely. "
https://www.universetoday.com/... [universetoday.com]
Let's just say it won't be leaving any time soon.
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To put evaporation times in perspective, the formula for a "simple" black hole is
Tev = 2.1*10^67 years * (M_hole / M_sun)^3 https://en.wikipedia.org/wiki/Hawking_radiation#Black_hole_evaporation
If we assumed an earth-mass black hole (3x10^-6 solar masses) then the evaporation time is about 569*10^48 years, or about 10^40x longer than the current age of the universe.
To evaporate a black hole in only twice the age of the universe it would need to have a mass of roughly 1.1e-19 solar masses, or 219e9kg - equi
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Quite true. So-called "quantum black holes" were suggested in various theories as being created at the Big Bang, but the evaporation of small black holes explains why they've not been found.
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Quite so - but while such small black holes might be a candidate for dark matter, they're not really relevant to statistical orbital anomalies within our solar system.
Meanwhile, relatively stable black holes can still be insanely tiny - that 600m cube of water, which is still far to small to appreciably influence orbits, would condense into a black hole with a Schwarzschild radius of only 324x10^-18 meters (=2GM/c^2), making it about 150,000x smaller than a hydrogen atom, or about 2/3 the diameter of a sing
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> that 600m cube of water, which is still far to small to appreciably influence orbits, would condense into a black hole
It wouldn't. It would take an outlandish pressure, present only at the start of the "Big Bang", to compress it that small.
> Even an Earth-mass black hole would have a diameter of about 18mm, making it a wonderful gravitational lens, or an easily contained power source
I'm afraid the science fiction definitions of "easily contained" are not practical in the real world.
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Sure, but I figured primordial black holes was what we were talking about, the water is just a reference mass.
As for containing an an Earth-mass black hole - tensile tidal forces at the center of a vertical rod are given by
F = u l m/4r3, where l is the vertical length, and m is the mass of the object, and u=GM ( https://en.wikipedia.org/wiki/... [wikipedia.org] )
or r = (u l m/4F)^1/3
And as a simple reference point, a 2m, 100kg person should be able to (un)comfortably survive a tensile force of 1000N - that's the ballpark
Occam's Razor -- Nope! (Score:3)
Mr. William of Ockham almost certainly would not approve of this wildly speculative theory, that Planet Nine is an exotic celestial body. Instead, the ol' boy would posit that more mundane answers are more likely. We've seen lots of rocky and gaseous things in our solar system, but we ain't never seen no exotic species of planetoids or planetesimals a floatin' round out yonder!
I tend to agree with Willie.
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Mr. William of Ockham almost certainly would not approve of this wildly speculative theory
Mr. Karl Popper would approve: the more wildly speculative, the easier to falsify.
Re: Occam's Razor -- Nope! (Score:2)
Well played!
Edward Witten, a theoretical physicist at the Inst (Score:1)
"a theoretical physicist at the Institute for Advanced Study in Princeton"
a? the man who basically invented string theory?
There is not much evidence for a Planet 9. (Score:5, Interesting)
But as it appears, it's pure selection bias. Hunting for objects so far away from the Sun can not be done with every observatory out there, you need some very large ones. And those have so many observations going on, that you can't use them the whole year for planet hunts. And thus, most planetary objects were discovered in January/February or June/July. It has more to do with observation time reserved on Earth than with the real distribution of Kuiper belt objects.
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Could SpaceX solve the plastic recycling problem we have with rockets?
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Yup, they already found additional KBOs [sciencealert.com] that break the bias, meaning Planet 9 probably doesn't exist.
A black hole in our solar system would be very luminous in radio and X-ray (emitted by accreted matter), and since we didn't find any such nearby objects already, it's weird that they even consider it.
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There are some very smart people that disagree with a lot of that.
If it really is a small black hole... (Score:4, Interesting)
Then as a species we have *totally* lucked out. Who needs Dyson Spheres when we can just throw garbage down our local, friendly black hole and get energy equivalent to a large amount of the rest mass of what you chucked in?
Kardashev Type II here we come! (OK, the chances of it really being a BH are microscopically small, but one can dream...)
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whats wrong with living in somones shed? (Score:2)
Seriously just a thought, if planet 9 did end up being a primordial black hole, what would the implications of that mean for the development of intelligent life else where?
Maybe having such a companion in some way helped shepherd objects away from the outer solar system much like Jupiter and Saturn do for the inner solar system, creating a rare one in a million combo that just isn't seen very often elsewhere giving life enough time to create being like us. It might explain why its oddly quite out there....
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Probably nothing.
A black hole would not really behave any differently than a planet of the same mass - except that most objects that would have hit the planet, will instead be slingshot around the black hole, possibly being spagettified in the process (aka reduced to gravel or dust, depending on how close they got) And given the immense distances and low orbital speeds of anything that far out, only a miniscule fraction of objects would be expected to collide with a planet.
No! (Score:2)
It isn't.
Gravitational lensing anyone? (Score:3)
Re: riffraff (Score:1)
Every hundred-thousandth of a second? (Score:2)
"Key to this plan would be the ability of the probes to keep pinging Earth precisely every hundred-thousandth of a second." (from the referenced article)
Well, the probes are not really "pinging" Earth and are broadcasting (one-way transmission) in a
Dark matter.. (Score:2)
Not a New Theory (Score:2)
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NO: Black Holes do not exist (Score:1)
It's a stupid idea (Score:1)
If it's a BH then it has a lot of mass to it. So much not even light can escape. If this were a planet as such, that means it's orbiting the Sun. Being a BH it would move the sun around. In fact the Sun would be slingshot around. In short, it would be a very big deal for something like that to come back in.
Then there are all the other problems with this.
There could be a BH out there in our for lack of a better term so people would understand - neighbourhood, it's not the 9th planet.