One place Planet 9 could be hiding

https://www.universetoday.com/165774/theres-one-last-place-planet-9-could-be-hiding/

by Brajeshwar • 2 years ago

66 76 2 years ago

api2• 2 years ago

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.

marcosdumay2• 2 years ago

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• 2 years ago

You don't move the blackhole+ship, that's crazy. You'd simply move the universe around your ship.

coffeebeqn3• 2 years ago

How would you move a black hole around?

mcswell3• 2 years ago

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.

kunrii8528• 2 years ago

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

api2• 2 years ago

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).

sparrowInHand2• 2 years ago

? Are you serious.

We have concepts for light driven probes now. They even can slow down, by ejecting a parabolic lightsail, that bounces light from the opposit direction back to them.

Its all lightweight and - way more feasable, if you abandon the " a human has to go there idea". Communication would be an issue, but otherwise...

codethief• 2 years ago

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 )

tejtm3• 2 years ago

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• 2 years ago

In that scenario, I'd love to see the kinds of cool relativistic time dilation experiments we could run on those probes.

jfengel2• 2 years ago

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• 2 years ago

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?

jvanderbot• 2 years ago

If you draw a box around the solar system, and want a fast moving BH to settle in without rejecting on hyperbolic orbit, you'd just have to throw out another object that's comparable in size, at comparable speed. Momentum conserved.

A near miss with one of Jupiters moons might sling the BH into an orbit at slower pace and throw that moon into, say, earth to create our own moon.

This stuff probably happens more often than we think, on a galactic time scale.

malfist• 2 years ago

I mean, Pluto is right there man

adastra222• 2 years ago

That would be Planet 12 :)

davidmurdoch• 2 years ago

Nah. It should have been grandfathered in as planet 9.

mrcartmeneses• 2 years ago

Pluto needs to up its game and become GRAVITATIONALLY DOMINANT!!!

fghorow• 2 years ago

Yeah, but this is Mike Brown we are talking about. The Don of the "Pluto is not a planet" mafia.

johnea• 2 years ago

It's obviously being hidden by the lizard people inside the hollow earth...

mondobe• 2 years ago

Obviously, the lizard people's base would be inside planet 9! Common sense, people.

kibwen• 2 years ago

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• 2 years ago

I hear there are many new machines on Ix.

moomin• 2 years ago

Leto II is the only person to get this joke.

dividefuel• 2 years ago

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• 2 years ago

“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.”

iszomer• 2 years ago

"Don't Panic."

14• 2 years ago

I like to tell people how big space is just by describing how fast voyager 1 is moving and how long it will take to reach 1 light year of travel. Voyager 1 launched back in the 70's and is traveling around 38,210 mph. Even at that speed it will take another approximate 18,500 years for it to reach it's first light year traveled. The closest star is about 4.2 light years away so at it's current speed it would take about 75,000 years for it to reach Alpha Centauri.The more you start getting into the numbers and things like how many light years across the milky way is and how far to the next galaxy and how many galaxies their are you start to see the universe is unimaginably large. I don't think one could fully grasp it's size. Amazing

halfcat• 2 years ago

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.

medstrom2• 2 years ago

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)

vikingerik2• 2 years ago

Existing would be the bigger surprise. We've ruled out anything of Earth's mass out to distances of 100 AU and Jupiter's mass to 1000 AU, since those would be visible to telescopic searches and have measurable gravitational effects on known objects that we don't see from observation. It's almost certain that there's nothing that would meet the "clearing the neighborhood" definition of a planet. At most there would be more dwarf planets on the size order of Pluto and Eris and Quaoar, which are common, but those are each comparatively tiny, like 0.2% of Earth's mass.

The article says "78% of places have been searched"... but that's a really weirdly imprecise way of saying that. What are "places" here? Like, the sphere out to 100 AU is 78% of the volume out to 120 AU... but that makes no sense, the possible locations go out to 1000 AU or more.

There are indeed lots of claims of some evidence for another planet existing... but all those claims are different with no consensus, and it's largely fairly specious proposals trying to get some funding.

sparrowInHand2• 2 years ago

Eh, we ruled that out - within our observable time-frame, but we do not know about exotic, long-term orbits. Like a 50.000 year elipse out into the ort cloud and back in.

fabiensanglard• 2 years ago

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?

coffeebeqn3• 2 years ago

All our eyes aren’t on Earths orbit

jfengel2• 2 years ago

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.

tejtm3• 2 years ago

There are uncoutably many binary star systems, one (or both) being the size of a sports ball changes nothing.

bee_rider2• 2 years ago

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.

mtlmtlmtlmtl2• 2 years ago

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.

andruby2• 2 years ago

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

wkat42422• 2 years ago

The premise there is also that the other earth developed in exactl synchronism until they discovered each other which is much less realistic :)

chasil• 2 years ago

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

coffeebeqn3• 2 years ago

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• 2 years ago

This does not seem most likely at all.

bee_rider2• 2 years ago

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• 2 years ago

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• 2 years ago

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?

mtlmtlmtlmtl2• 2 years ago

This is about a different hypothesised planet beyond Neptune.

dgrin912• 2 years ago

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.

medstrom2• 2 years ago

What is this reasoning? A scientific hypothesis can fit in one sentence on the back of a napkin, certainly it can in a youtube short too.

fragmede• 2 years ago

His biggest contributions are in science communications towards younger and non-science oriented people.

that's a huge contribution and not to be undervalued!

7734128• 2 years ago

Please don't spread YouTube Shorts. It's polluting the internet.

opello• 2 years ago

https://www.mrfdev.com/enhancer-for-youtube

This has an option to makes Shorts less objectionable, in addition to allowing control over a lot of the things in the YouTube experience that I find annoying anyway.

bbsz• 2 years ago

There's a good overview of history of discoveries of planets (and other types of objects) in the solar system: https://www.youtube.com/watch?v=J_KCbyGkNuY

You can arrow through it to just have a look at the slides. At 39 minute presenter talks about extreme orbits that made some of the objects hard to discover for decades.

autokad• 2 years ago

its in Pluto's orbit. mainly because Pluto is planet 9.

wyldfire• 2 years ago

Have you checked across the 8th dimension? Ask any Lectroid, they'll tell you.

tiahura• 2 years ago

How can we spot exoplanets 20M light years away, but not have absolute metaphysical certitude about the number of planets in the solar system?

ivanjermakov• 2 years ago

Not sure where 20M l.y. are coming from, because the farthest exoplaned seems to be 27k l.y. from the Sun: https://en.wikipedia.org/wiki/SWEEPS-11

Regarding your question, perhaps it's harder to perform direct imaging of a planet in the solar system than of an exoplanet against its local star(s). In the first case, relative motion is much higher.

vikingerik2• 2 years ago

1) We spot exoplanets by their influence on the star, which is nearly nil at distances of 100+ AU.

2) We spot exoplanets that have huge volumes and masses, like Neptune or Jupiter size (15x or 100x Earth's mass, or even multiples of Jupiter), but the ones we're talking about beyond the Kuiper belt might be on the order of 0.1 Earth mass or smaller.

3) 20M light years is an exaggeration, most detected planets are within 1000 light years.

One place Planet 9 could be hiding

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