The abstract from the paper[1] linked to from the article is a good read and short, so I think it is worth quoting here:
"The existence of a giant planet beyond Neptune -- referred to as Planet Nine (P9) -- has been inferred from the clustering of longitude of perihelion and pole position of distant eccentric Kuiper belt objects (KBOs). After updating calculations of observational biases, we find that the clustering remains significant at the 99.6\% confidence level. We thus use these observations to determine orbital elements of P9. A suite of numerical simulations shows that the orbital distribution of the distant KBOs is strongly influenced by the mass and orbital elements of P9 and thus can be used to infer these parameters. Combining the biases with these numerical simulations, we calculate likelihood values for discrete set of P9 parameters, which we then use as input into a Gaussian Process emulator that allows a likelihood computation for arbitrary values of all parameters. We use this emulator in a Markov Chain Monte Carlo analysis to estimate parameters of P9. We find a P9 mass of 6.2 (+2.2, −1.3) Earth masses, semimajor axis of 380 (+140,−80) AU, inclination of 16±5∘ and perihelion of 300+85−60 AU. Using samples of the orbital elements and estimates of the radius and albedo of such a planet, we calculate the probability distribution function of the on-sky position of Planet Nine and of its brightness. For many reasonable assumptions, Planet Nine is closer and brighter than initially expected, though the probability distribution includes a long tail to larger distances, and uncertainties in the radius and albedo of Planet Nine could yield fainter objects."
Or is it just a matter of us not spending the time/effort to find it. I know time on instruments like Hubble is very, very tight and scheduled out years in Advance. But they have been talking about Planet X since like the 80s at least, and probably earlier.
Even Pluto was detectable relatively early and it’s on a crazy orbital plane and elliptical orbit.
It could, the relevant part of the whole thing is the object's mass (and therefore its gravitational influence) and its orbit.
Lex Fridman did a podcast interview a few months ago with Konstantin Batygin [0] about the topic of Planet Nine and he poses this exact question of whether or not it could be a black hole [1].
More specifically, he asks if it could be a primordial black hole which would make it a double discovery since primordial black holes are still only theoretical.
It won't even start to decay until space expands enough that it's warmer than the cosmological background, not that that's more than a rounding error to your calculation.
Counter argument against the black hole hypothesis includes the lack of powerful x-ray activity where the black hole should be. Also, its size would be quite unusual, which in that case could be a primordial black hole, which in itself is theoretical and never been observed.
If it were a black hole, which would necessarily mean a primordial black hole, we would never spot it. We would look, and look, and eventually give up and say it must be a statistical fluke. A coal-black body would also be hard to spot. Surprisingly many asteroids are black, for poorly-understood reasons.
We might not spot it from earth, but if we’re confident enough of where we’ll find it, its orbital parameters, its mass, a probe could be sent, and it could be detected through its SOI, and perhaps even direct observation.
Sure, ~300AU is a long way, but we have the technology, and it’s our closest black hole candidate by many orders of magnitude
If it is a choice between, (1) Spend $500M just to see whether there really is a black hole there, or (2) it is probably a just statistical fluke -- it is not hard to guess which will be chosen.
Probably. It narrows down the range of locations and therefore the search area. And given the potentially very low brightness of the object, search area and hence telescope time are limiting factors.
Probably not. This planet would be about 10 times as far away from us as Pluto, and estimated brightness is about 1/1000th that of Pluto. And its low velocity would make it much harder to pick out against the stellar background.
In Cartoons (and in science), wasn't this called Planet X and in other hypothesis 'Nemesis'?
I get that Pluto was demoted, but it's still a planet, if dwarfish, so it should still be Planet X (X as in ten, but X can also mean undetermined number, which is perfect).
Comments
The abstract from the paper[1] linked to from the article is a good read and short, so I think it is worth quoting here:
"The existence of a giant planet beyond Neptune -- referred to as Planet Nine (P9) -- has been inferred from the clustering of longitude of perihelion and pole position of distant eccentric Kuiper belt objects (KBOs). After updating calculations of observational biases, we find that the clustering remains significant at the 99.6\% confidence level. We thus use these observations to determine orbital elements of P9. A suite of numerical simulations shows that the orbital distribution of the distant KBOs is strongly influenced by the mass and orbital elements of P9 and thus can be used to infer these parameters. Combining the biases with these numerical simulations, we calculate likelihood values for discrete set of P9 parameters, which we then use as input into a Gaussian Process emulator that allows a likelihood computation for arbitrary values of all parameters. We use this emulator in a Markov Chain Monte Carlo analysis to estimate parameters of P9. We find a P9 mass of 6.2 (+2.2, −1.3) Earth masses, semimajor axis of 380 (+140,−80) AU, inclination of 16±5∘ and perihelion of 300+85−60 AU. Using samples of the orbital elements and estimates of the radius and albedo of such a planet, we calculate the probability distribution function of the on-sky position of Planet Nine and of its brightness. For many reasonable assumptions, Planet Nine is closer and brighter than initially expected, though the probability distribution includes a long tail to larger distances, and uncertainties in the radius and albedo of Planet Nine could yield fainter objects."
[1] https://arxiv.org/abs/2108.09868
Question. Does it have to be a planet out there?
Could it be a small black hole?
Or is it just a matter of us not spending the time/effort to find it. I know time on instruments like Hubble is very, very tight and scheduled out years in Advance. But they have been talking about Planet X since like the 80s at least, and probably earlier.
Even Pluto was detectable relatively early and it’s on a crazy orbital plane and elliptical orbit.
It could, the relevant part of the whole thing is the object's mass (and therefore its gravitational influence) and its orbit.
Lex Fridman did a podcast interview a few months ago with Konstantin Batygin [0] about the topic of Planet Nine and he poses this exact question of whether or not it could be a black hole [1].
More specifically, he asks if it could be a primordial black hole which would make it a double discovery since primordial black holes are still only theoretical.
[0] https://www.youtube.com/watch?v=tm7poMupE8k
[1] https://www.youtube.com/watch?v=tm7poMupE8k&t=4757s
The odds are incredibly tiny for it to be anything other than a planet.
It could be, but it would be the size of a tennis ball. See https://news.ycombinator.com/item?id=28167058
According to my calculations it would take more than 10^53 years to decay.
It won't even start to decay until space expands enough that it's warmer than the cosmological background, not that that's more than a rounding error to your calculation.
Counter argument against the black hole hypothesis includes the lack of powerful x-ray activity where the black hole should be. Also, its size would be quite unusual, which in that case could be a primordial black hole, which in itself is theoretical and never been observed.
If it were a black hole, which would necessarily mean a primordial black hole, we would never spot it. We would look, and look, and eventually give up and say it must be a statistical fluke. A coal-black body would also be hard to spot. Surprisingly many asteroids are black, for poorly-understood reasons.
We might not spot it from earth, but if we’re confident enough of where we’ll find it, its orbital parameters, its mass, a probe could be sent, and it could be detected through its SOI, and perhaps even direct observation.
Sure, ~300AU is a long way, but we have the technology, and it’s our closest black hole candidate by many orders of magnitude
If it is a choice between, (1) Spend $500M just to see whether there really is a black hole there, or (2) it is probably a just statistical fluke -- it is not hard to guess which will be chosen.
Could yes. But it certainly is not the easiest explanation.
Sounds like a great start. Does this help us (as a species) collect data in a more focused way to narrow the search?
Probably. It narrows down the range of locations and therefore the search area. And given the potentially very low brightness of the object, search area and hence telescope time are limiting factors.
Given that Pluto was discovered by such a relatively small telescope, I wonder if this is something amateur astronomers can contribute to.
Probably not. This planet would be about 10 times as far away from us as Pluto, and estimated brightness is about 1/1000th that of Pluto. And its low velocity would make it much harder to pick out against the stellar background.
In Cartoons (and in science), wasn't this called Planet X and in other hypothesis 'Nemesis'?
I get that Pluto was demoted, but it's still a planet, if dwarfish, so it should still be Planet X (X as in ten, but X can also mean undetermined number, which is perfect).
Nemesis is a hypothetical star, not Planet 9/X, explaining different phenomena; it would be farther out.
But, yes, Planet 9 is more recent name for the same hypothetical object as Planet X:
https://solarsystem.nasa.gov/planets/hypothetical-planet-x/i...