[HN Gopher] One place Planet 9 could be hiding
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One place Planet 9 could be hiding
Author : Brajeshwar
Score : 52 points
Date : 2024-02-19 14:51 UTC (8 hours ago)
(HTM) web link (www.universetoday.com)
(TXT) w3m dump (www.universetoday.com)
| api wrote:
| I've always thought the idea of planet nine being a primordial
| black hole was kinda cool, but AFAIK we have no evidence to
| suggest this.
|
| Unless I'm mistaken if PBHs do exist then one with 2-4 Earth
| masses is within the plausible range. It'd be about the size of a
| billiard ball. The existence of lots and lots of PBHs of various
| sizes is one dark matter candidate.
|
| https://en.wikipedia.org/wiki/Primordial_black_hole
|
| If there were such a thing out there we could send a probe to it.
| I can't imagine what kinds of interesting physics we could do if
| we could directly examine a black hole.
|
| It'd be neat if it were actually _useful_ in the far future too,
| like as a power source to generate and beam energy to
| interstellar spacecraft. There 's even concepts like this:
|
| https://en.wikipedia.org/wiki/Black_hole_starship
|
| A PBH of that mass would not be useful for this but perhaps
| there'd be a way to leverage the extreme conditions created near
| the event horizon to generate smaller ones that evaporate
| quickly... like the extreme physics analog of sourdough starter.
| marcosdumay wrote:
| The idea of a black hole starship is that you carry the black
| hole around, just like any other engine. If you want to beam
| power from it, there isn't anything at all there to gain
| compared to beaming power from the Sun.
|
| And if you want to carry it with your ship, it weighting 2
| Earth masses is kind of a drawback.
| djbusby wrote:
| You don't move the blackhole+ship, that's crazy. You'd simply
| move the universe around your ship.
| coffeebeqn wrote:
| How would you move a black hole around?
| calamari4065 wrote:
| Just get out and push
| marcosdumay wrote:
| AFAIK, the most popular answer is to give it an electrical
| charge.
|
| I really don't know how are you supposed to maintain that
| change long-term. But then, it's similar to the problem of
| deciding whether the emissions from the black hole are
| particles that you can focus around, so I guess it's an
| open problem.
| mcswell wrote:
| There was a scifi story decades ago about using small but
| heavy objects (neutronium, IIRC) as an integral part of space
| ships. The idea was not to use them to generate energy, but
| to generate a gravitational field to counteract the effects
| on humans of high acceleration. The object was held in front
| of the spacecraft, and would be moved closer when high
| acceleration was needed.
|
| I guess if the ship was just drifting, you'd have the heavy
| object at a sufficient distance to cause ~1g gravity.
|
| I don't remember the story's title or author(s), but it
| likely appeared in Analog.
| at_a_remove wrote:
| It's Charles Sheffield, in particular his McAndrew series.
| mcswell wrote:
| Thank you! With that help, I was able to find the story:
| "Moment of Inertial." And here's a link to the story: htt
| ps://www.baen.com/Chapters/067157857X/067157857X__2.htm
| kunrii8528 wrote:
| There are far more feasible alternatives to deep space
| propulsion that could actually work now, and all you have to do
| is detonate a couple of nukes.
|
| https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
|
| See also its cousin:
|
| https://www.centauri-dreams.org/2012/07/20/medusa-nuclear-pu...
|
| You can even try these in KSP with mods afaik
| api wrote:
| Yeah I'm familiar with the old "Devil's pogo stick."
| Apparently thermonuclear Orion could achieve as high as 10%
| the speed of light, which would get you to the Centauri
| system within a single human life span (barely).
| codethief wrote:
| > If there were such a thing out there we could send a probe to
| it.
|
| You might be interested in Ed Witten's paper about this topic:
| "Searching for a Black Hole in the Outer Solar System",
| https://arxiv.org/abs/2004.14192
|
| (See also this related comment from the HN discussion back then
| which puts Witten's paper into context very nicely:
| https://news.ycombinator.com/item?id=23135031 )
| tejtm wrote:
| A PBH that size would be extremely useful for getting out of
| (and back into) our solar system, at least for probes that
| could survive being slingshot to a fraction of light speed. It
| could be like slingshoting around the sun, but but at a few
| miles from the core instead of a million miles.
| Zee2 wrote:
| In that scenario, I'd love to see the kinds of cool
| relativistic time dilation experiments we could run on those
| probes.
| jfengel wrote:
| It's hard to imagine a scenario in which the solar system
| captures a wandering black hole. If it comes in it's going to
| keep going, or take the hyperbola back out the way it came.
|
| It's not impossible and such scenarios can be constructed. But
| they're really narrow and it's hard to justify putting a lot of
| effort into looking for wild coincidences.
| thegrim33 wrote:
| Maybe you could elaborate? As the solar system already
| contains bodies with masses both smaller and larger than the
| primordial black holes mentioned, what would be the issue?
| roywiggins wrote:
| all of the stuff I'm the Solar system that we know about
| probably was here from the beginning, forming out of the
| same cloud of dust that produced the sun. A black hole
| would have to wander in from elsewhere and somehow get
| captured rather than zipping by on a hyperbolic orbit.
| scheme271 wrote:
| The relative velocity of stuff that wasn't in the cloud
| that formed the solar system would almost certainly be
| really high. So it would take a lot to capture the an
| extra-solar body. Any bodies from outside the solar system
| would probably either travel straight through the solar
| system or do something like what `Oumuamua did.
| malfist wrote:
| I mean, Pluto is right there man
| adastra22 wrote:
| That would be Planet 12 :)
| davidmurdoch wrote:
| Nah. It should have been grandfathered in as planet 9.
| svachalek wrote:
| If you want to stand on tradition, planet 9 has to go to
| Ceres.
| adastra22 wrote:
| Yeah that's where 12 comes from. IIRC it was the 12th
| known "planet" when it was discovered, if you include
| spherical, gravitationally differentiated asteroids.
|
| The air quotes are because by the geophysical definition
| of planet (the only scientifically reasonable definition,
| fight me) our Moon, the Galilean moons of Jupiter, and
| Titan are all also planets, and I think they were known
| at that time.
|
| Our solar system likely contains thousands of planets. I
| wish people could get excited over that rather get stuck
| up about tradition and "how will kids ever remember them
| all?" My kids can name the stats and special powers of
| 350 Pokemon. They'll be just fine.
| mrcartmeneses wrote:
| Pluto needs to up its game and become GRAVITATIONALLY
| DOMINANT!!!
| fghorow wrote:
| Yeah, but this is Mike Brown we are talking about. The Don of
| the "Pluto is not a planet" mafia.
| johnea wrote:
| It's obviously being hidden by the lizard people inside the
| hollow earth...
| mondobe wrote:
| Obviously, the lizard people's base would be inside planet 9!
| Common sense, people.
| kibwen wrote:
| _> continues to search for the elusive Planet Nine (also called
| Planet X)_
|
| In light of Pluto's demotion, surely we should deprecate "Planet
| X" in favor of "Planet Ix".
| time0ut wrote:
| I hear there are many new machines on Ix.
| moomin wrote:
| Leto II is the only person to get this joke.
| tizio13 wrote:
| Ixian Ambassador Hwi Noree walks on a bridge...
| dividefuel wrote:
| Would it be a bigger surprise if Planet 9 existed, or if Planet 9
| doesn't exist? This isn't my field of study, but as I understand
| there's a good amount of indirect evidence for a Planet 9... and
| still no direct proof. Assuming we're searching in the right
| areas, if a scan of the first 80% didn't reveal it, it seems
| unlikely (but of course not impossible) that we'll find it in the
| last 20%.
| pmcf wrote:
| "Space is big. You just won't believe how vastly, hugely, mind-
| bogglingly big it is. I mean, you may think it's long way down
| the road to the chemist's, but that's just peanuts to space."
| halfcat wrote:
| There's a difference between completing 80% of the work, and
| ruling out 80% of the options.
|
| We could rule out 80% of the options and still have 99% of the
| work yet to be completed.
|
| Like if we're looking for a bacteria on the land surface of the
| earth, and we rule out 80% of the options, that leaves us with
| searching an area the size of Africa for a microscopic life
| form.
| medstrom wrote:
| Doesn't change the fact that whatever probability you
| previously assigned to finding Planet 9, it should be one
| fifth of that now. (Sort of. Not so drastic if you have
| strong reasons to think there is a Planet 9)
| fabiensanglard wrote:
| I wonder if it could be opposite from us, on the other side of
| the Sun.
|
| Rotating at the same speed and hence never observable?
| coffeebeqn wrote:
| All our eyes aren't on Earths orbit
| jfengel wrote:
| It couldn't be stable there for very long. It's a three body
| problem. If it ever existed it would have been ejected billions
| of years ago.
| tejtm wrote:
| There are uncoutably many binary star systems, one (or both)
| being the size of a sports ball changes nothing.
| tejtm wrote:
| https://duckduckgo.com/?q=estimated+percentage+of+binary+st
| a...
| bee_rider wrote:
| It would have to be orbiting at the same distance as the Earth
| to have the same speed, which seems unlikely, and only gives it
| a fairly small amount of space to live in, so I'm sure we've
| checked there.
|
| The hypothetical planet 9 is speculated to be far from the sun,
| past Pluto.
| mtlmtlmtlmtl wrote:
| If you mean on the opposite side, in the same orbit(in the
| earth-sun L3), this has been hypothesised as far back as the
| presocratic Greeks(https://en.wikipedia.org/wiki/Counter-
| Earth), but we now have a lot of evidence that it isn't there.
|
| Also, planet 9 was hypothesised in order to explain the orbits
| of transneptunian objects, which an antiearth wouldn't do.
|
| If you mean behind the sun on a completely different orbit,
| well it wouldn't stay behind the sun relative to us forever,
| and likely would only very rarely be obscured by the sun.
| andruby wrote:
| Have you seen the movie Another Earth (2011)?
|
| That's the exact plot.
|
| It's not realistic (space probes would have "seen" the other
| earth), but does make for an interesting film.
|
| https://en.m.wikipedia.org/wiki/Another_Earth
| chasil wrote:
| We would certainly see something that is six times the mass of
| the earth sharing our orbit.
|
| The wiki estimates the missing planet to be 6.3 times as
| massive as the Earth, could be up to 2.3 times more or -1.5
| times less than this figure.
|
| "Based on earlier considerations, this hypothetical super-
| Earth-sized planet would have had a predicted mass of five to
| ten times that of the Earth, and an elongated orbit 400 to 800
| times farther from the Sun than the Earth is."
|
| https://en.wikipedia.org/wiki/Planet_Nine
| coffeebeqn wrote:
| Most likely explanation is that Planet 9s population is a higher
| level civilization that understands the "dark forest" hypothesis.
| They're probably nervously eyeing their noisy neighbors
| JohnMakin wrote:
| This does not seem most likely at all.
| bee_rider wrote:
| That seems like the most interesting sci-fi plot explanation.
| Two alternative explanations for why we can find Planet 9 could
| be: it is a tiny, hard to see rock very far away, or it doesn't
| exist.
| sliken wrote:
| Neil deGrasse Tyson, an astrophysicist, claims [0] that if you
| remove one observatories data, that the anomaly that leads to the
| conclusion there's a planet 9 disappears.
|
| [0] https://www.youtube.com/shorts/RvNYL5sPItc
| pmontra wrote:
| Maybe the name of that observatory was too long to fit in that
| 59 seconds video. Do you have any idea about which observatory
| it is?
| mtlmtlmtlmtl wrote:
| This is about a different hypothesised planet beyond Neptune.
| dgrin91 wrote:
| He also tends to be full of hot air. His biggest contributions
| are in science communications towards younger and non-science
| oriented people. I'm not saying he is wrong or lying or
| anything like that, but a youtube short is not a good standin
| for a scientific hypothesis.
| 7734128 wrote:
| Please don't spread YouTube Shorts. It's polluting the
| internet.
| autokad wrote:
| its in Pluto's orbit. mainly because Pluto is planet 9.
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