The Orbit of Planet Nine(findplanetnine.blogspot.com)
findplanetnine.blogspot.com
The Orbit of Planet Nine
https://findplanetnine.blogspot.com/2021/08/the-orbit-of-planet-nine.html
84 comments
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.
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.
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 be, but it would be the size of a tennis ball. See https://news.ycombinator.com/item?id=28167058
> Could it be a small black hole?
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
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.
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.
[deleted]
Could yes. But it certainly is not the easiest explanation.
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
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.
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).
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).
> In Cartoons (and in science), wasn't this called Planet X and in other hypothesis 'Nemesis'?
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...
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...
> Put these two plots together and you get a 99.6% chance that the objects are clustered, rather than uniform. That sounds pretty good to me.
That's not even three-sigma. I'm not sure if this is real evidence of a planet nine. Just a chance alignment of orbits seem like the most plausible explanation.
That's not even three-sigma. I'm not sure if this is real evidence of a planet nine. Just a chance alignment of orbits seem like the most plausible explanation.
question:
How far out can a planet be if it has a roughly circular orbit? At some point outwards neighboring heavy things will make it unstable.
How far out can a planet be if it has a roughly circular orbit? At some point outwards neighboring heavy things will make it unstable.
The oort cloud that is theorized to exist is hypothesized to be up to several lightyears out.
https://en.wikipedia.org/wiki/Oort_cloud
https://en.wikipedia.org/wiki/Oort_cloud
It seems to me that something that's a couple of lightyears out can't have any sort of stable orbit. I suppose that an Oort cloud essentially merges with an adjacent star's so there's no hard definition.
At the point of merger with neighboring stars it’s likely that circular orbits are unstable.
Judging by our own solar system it’s likely that the distance at which circular orbits are stable is a question of relative mass, and time.
Judging by our own solar system it’s likely that the distance at which circular orbits are stable is a question of relative mass, and time.
> there's no hard definition.
Yes. All human definitions are imperfect.
Yes. All human definitions are imperfect.
Do other systems have oort clouds or are their’s also something we cant see from this far
The only physical evidence we have they exist are comets that occasionally show up in the inner solar system where we could observe them which have orbits that are not interstellar but would put them as going incredibly far out. From that we can extrapolate that they likely exist around every star but there is no way we could verify that with our current technology since any light reflected off the objects would be far too faint to detect.
> https://en.wikipedia.org/wiki/Oort_cloud
The distances between the planets fit nicely on a log scale.
The distances between the planets fit nicely on a log scale.
This limit is called the Hill Sphere: https://en.wikipedia.org/wiki/Hill_sphere
For the Sun it's a bit more than 1 light year, but in practice almost all orbits will be quite a bit under this: less than 0.8 ly.
For the Sun it's a bit more than 1 light year, but in practice almost all orbits will be quite a bit under this: less than 0.8 ly.
The Hill Sphere also changes over time as stars pass us. The galaxy is more of a soup - the stars in the neighborhood don't have a static position to one another.
...so I would imagine that anything even 1ly out would be unstable, over several hundred million years. Solar systems may even exchange very outer outer "planets".
...so I would imagine that anything even 1ly out would be unstable, over several hundred million years. Solar systems may even exchange very outer outer "planets".
What is the distribution (relative to galactic center) of TNOs used for calculation?
I love the way this is written. It's like the author, as a scientist, is in the service of humanity. The tone, language, the tongue in cheek apology...
Something very noble and approachable to it. Good job. Find that planet for us! We appreciate it.
Something very noble and approachable to it. Good job. Find that planet for us! We appreciate it.
The writing is great, but I keep wondering: Why do so many physicists use Jet or other non-perceptually uniform rainbow-like colourmaps for their graphs? Shouldn't that be part of great science communication, given that about 1 in 12 men have some form of colour blindness?
There are so many other visually appealing options [0] that are attractive while still being perceptually uniform. There's even Google's Turbo [1] colourmap for those who refuse to give up rainbow-like colourmaps.
[0]: https://matplotlib.org/stable/tutorials/colors/colormaps.htm...
[1]: https://ai.googleblog.com/2019/08/turbo-improved-rainbow-col...
There are so many other visually appealing options [0] that are attractive while still being perceptually uniform. There's even Google's Turbo [1] colourmap for those who refuse to give up rainbow-like colourmaps.
[0]: https://matplotlib.org/stable/tutorials/colors/colormaps.htm...
[1]: https://ai.googleblog.com/2019/08/turbo-improved-rainbow-col...
Short answer: because none of them is the default in standard plotting tool.
There is so many alternative that it is hard to know which replacement you should pick. If you pick the wrong one you are a moron, if you stick with the bad default it's way less noticeable, even if it is a strictly worse choice.
There is so many alternative that it is hard to know which replacement you should pick. If you pick the wrong one you are a moron, if you stick with the bad default it's way less noticeable, even if it is a strictly worse choice.
The default issue is certainly keenly felt. My first scientific publication graphs were done with Jet. But since switching to some of the perceptually uniform ones (most often Viridis), I've never had a complaint.
But your point "if you stick with the bad it's way less noticeable" is understandable.
But your point "if you stick with the bad it's way less noticeable" is understandable.
Matplotlib 2.0 came out in January 2017 and has a perceptually uniform, colorblond friendly colormap as default and three others available.
There is no exclude for using Jet today and Journals should reject papers using bad colormaps
There is no exclude for using Jet today and Journals should reject papers using bad colormaps
"...given that about 1 in 12 men have some form of colour blindness?"
I guess women are better suited to science work after all. ;)
I guess women are better suited to science work after all. ;)
This feels overengineered...
Since it's showing a probability density, wouldn't it make most sense to just use a grayscale in this case? As the probability density approaches zero the visual would disappear as well. This is more intuitive, as the probability is zero off the edge of the graph/page
I think you only need this color vomit if you have a change between two states, or you have multiple intermediary states and want some visual "clustering".
You can actually see the problem very clearly b/c it ends up having a weird dark-blue to white cut is some of the plots.
Since it's showing a probability density, wouldn't it make most sense to just use a grayscale in this case? As the probability density approaches zero the visual would disappear as well. This is more intuitive, as the probability is zero off the edge of the graph/page
I think you only need this color vomit if you have a change between two states, or you have multiple intermediary states and want some visual "clustering".
You can actually see the problem very clearly b/c it ends up having a weird dark-blue to white cut is some of the plots.
The advantage of using a rainbow scale as opposed to a gray scale is that a rotation in hue space brings out more 'detail' than a simple black to white gradient.
that's an interesting point
I still think it's a bit visually confusing when you're representing the existence or non-existence of something (the planet is in this region, and not anywhere else)
You could in theory do both.. rotate in hue and fade to white. If you did it right, when if you printed it out in B&W you'd get the grayscale equivalent :)
Maybe it'd look a bit silly
I still think it's a bit visually confusing when you're representing the existence or non-existence of something (the planet is in this region, and not anywhere else)
You could in theory do both.. rotate in hue and fade to white. If you did it right, when if you printed it out in B&W you'd get the grayscale equivalent :)
Maybe it'd look a bit silly
There are colormaps that are designed to do exactly this, for example the linear maps here: https://colorcet.com/userguide/index.html
That was a very interesting read. Thank you for sharing. I could really use some of the other color spaces presented too.. in some other situations.. I'll just need to figure out how to plug them into my workflow :)
It's strange but the first linear color space (CET-L03 red-yellow-white) seems to go to a lightness of 100. On the far right it looks white as expected. However the other one (CET-L20) looks very nice, but it doesn't seem to reach 100. Even though in the plots and explanation it suggests it does. Strange..
It's strange but the first linear color space (CET-L03 red-yellow-white) seems to go to a lightness of 100. On the far right it looks white as expected. However the other one (CET-L20) looks very nice, but it doesn't seem to reach 100. Even though in the plots and explanation it suggests it does. Strange..
You're welcome! I've also found https://github.com/1313e/CMasher
The more I look into this the more it seems this inevitably (accidentally or intentionally) misrepresents data. Even the author highlights how it does this. All the options are in some ways effectively thresholding/binning ... but in non-systematic ways through the vagaries of the human visual system. Unless this is an art project, there are more systematic and honest ways to bin things.
I can see how it can be useful or even inescapable in some situations.. The most obvious being maps with different content that needs to be distinct and of course these bimodal "divergent color maps". But maps are already half-art :) and bimodal data you're effectively vaguely "pre-binned" the data into two equal halves. There are also situations where the color is adding an extra dimension (like these "cyclic colour maps"). The result with the fingerprint is honestly hard to visually interpret, but I don't see any clear alternative (other than a grid of arrows I guess)
But reading all this stuff leaves me with the impression that colors are dangerous. They really should be last resort. In simple/common situation like the probability densities of the mystery planet - grayscale looks like it's the only really honest option. Side by side with the grayscale, the linear colors don't seem to be adding all that much and are creating artificial "islands" (not to mention the colors are a real blast to the eyeballs)
I can see how it can be useful or even inescapable in some situations.. The most obvious being maps with different content that needs to be distinct and of course these bimodal "divergent color maps". But maps are already half-art :) and bimodal data you're effectively vaguely "pre-binned" the data into two equal halves. There are also situations where the color is adding an extra dimension (like these "cyclic colour maps"). The result with the fingerprint is honestly hard to visually interpret, but I don't see any clear alternative (other than a grid of arrows I guess)
But reading all this stuff leaves me with the impression that colors are dangerous. They really should be last resort. In simple/common situation like the probability densities of the mystery planet - grayscale looks like it's the only really honest option. Side by side with the grayscale, the linear colors don't seem to be adding all that much and are creating artificial "islands" (not to mention the colors are a real blast to the eyeballs)
With a likely magnitude of ~21, it's seems out of reach for amateur hunters
What about watching for occultations of the stellar background over time in the suspect area and using software to blink compare?
Very very unlikely.
Relative to the Earth, P9 and background stars don't move much at all relative to one another.
Relative to the Earth, P9 and background stars don't move much at all relative to one another.
Reminds me of a documentary (which I can't find anymore) about New Horizons and the hunt for Ultima Thule, where the scientists did the exact same thing!
Wonder if you could take a NN and train it to deduce large body pathways from physic simulations like https://universesandbox.com/.
Then pump the known history of the solar system in and find out with what it fills the gap.
Probably not due to nine being such a outlier, would have to arrange the model to not filter out rare events.
Then pump the known history of the solar system in and find out with what it fills the gap.
Probably not due to nine being such a outlier, would have to arrange the model to not filter out rare events.
Yes, and modern methods would be really easy to incorporate because of awesome open source libraries.
If you got really lucky, there could be public data from telescopes that had already recorded whatever regions of space were of interest, and evidence of planet nine might have been disregarded as noise.
If you got really lucky, there could be public data from telescopes that had already recorded whatever regions of space were of interest, and evidence of planet nine might have been disregarded as noise.
Is this something NNs could do? The output might just be a probability field of orbits, which would not tell you anything more than known analytical methods would.
People are being conditioned to apply NNs to every problem, regardless of their suitability. Having to only think about a single tool makes everything easier.
I mean, based just on the abstract that's not entirely unlike what they're doing, except that they're using GP emulation.
> 6.2/+2.2/-1.3 Earth masses
What is this telling me?
What is this telling me?
That looks like an asymmetric error bar, meaning the best estimate is 6.2 but could be 2.2 above or 1.3 below.
Essentially it's a common physical scientist way of expressing a point estimate with a confidence interval. (In the life and social sciences they tend to just provide the point estimate and confidence interval explicitly.)
Essentially it's a common physical scientist way of expressing a point estimate with a confidence interval. (In the life and social sciences they tend to just provide the point estimate and confidence interval explicitly.)
Seems like an uneven error interval? Meaning if it’s not our estimated valid of 6.2, we have less confidence in the upper bound than the lower bound, or our estimates are distributed nonuniformly
Which makes sense since physical quantities like this can't be negative and so can't be normally distributed.
Planet Nine (supposedly) has a mass somewhere between 4.9-8.4x that of our own planet.
How likely is that there are multiple smaller planets instead of one 9th, on the same side working as offset?
Given how far out they are, how far off the solar system axis, and how small, it's definitely possible that there are multiple objects.
They’d have different orbits with different orbital periods so wouldn’t stay “on the same side” over millions of years.
Unless they were a double-planet, similar to Pluto/Charon. (Those orbit a common center not inside either body.) To my knowledge, they are unique, in that, among known bodies, though it would not be surprising if there were a few tiny double asteroids.
Since we are talking about ~350AU (Pluto is at ~40AU), that may very well be the case.
An easy approximation:
https://www.sjsu.edu/faculty/watkins/bode.htm
An easy approximation:
https://www.sjsu.edu/faculty/watkins/bode.htm
What if it's a planet temporarily captured by our solar system which is currently deataching due to an unstable orbit? Moons are temporary, why not planets, even suns.
Orbits don't just detach. Even at the predicted aphelion distance of 460 AU, P9 would have an orbital velocity of 1.4 km/s and a solar escape velocity of 2 km/s. So to detach from solar orbit you would need a minimum delta-v of 600 m/s. 600 m/s on a planet size object is only going to happen if a star happens to wander through the solar system.
It's possibly a transient object - ie not in orbit around the sun, but just passing through.
For all we know it formed billions of years ago in another system, and then was ejected from its home system from some near miss with its sister gas giant.
For all we know it formed billions of years ago in another system, and then was ejected from its home system from some near miss with its sister gas giant.
My understanding was that it had to be in orbit for a long time to cause the observed pattern, but you could be right.
> We find a P9 mass of 6.2 (+2.2, −1.3) Earth masses
This wouldn't even be half the mass of the smallest gaseous planet, but would be much larger than the largest terrestrial planet. Which do astronomers think it would be?
This wouldn't even be half the mass of the smallest gaseous planet, but would be much larger than the largest terrestrial planet. Which do astronomers think it would be?
It would be rocky.
It would be of a temperature where most things are rocks.
If it's not Hydrogen, it's rocks.
If it's not Hydrogen, it's rocks.
Either way, it would be very useful for inferring the properties of extrasolar planets in that size range.
Since it would be frozen, it would be hard to call it a gaseous planet. Even water, nitrogen, and oxygen are rocks, out there.
For comparison : Pluto is 40 AU from sun, against P9's 400 AU. 10 times further.
And 6 times mass of earth. Where Uranus and Neptune are x15 of earth.
Inclination 6 degrees are comparable with other planets.
And 6 times mass of earth. Where Uranus and Neptune are x15 of earth.
Inclination 6 degrees are comparable with other planets.
Ah... that will make it very hard to detect even with the largest telescopes, unless we have some specific coordinates.
Makes you wonder if maybe the interstellar space is just filled with tons of these little rocky planets.
Makes you wonder if maybe the interstellar space is just filled with tons of these little rocky planets.
Veritasium did a video about Planet 9 [1] with one of the authors of this article, Konstantin Batygin. It also features David Jewitt with opposing arguments regarding the existence of Planet 9.
[1]: https://youtu.be/pe83T9hISoY
[1]: https://youtu.be/pe83T9hISoY
It sounds like the opposing arguments are: (1) if you want something to exist, you'll be biased in your observations, (2) we might simply be unaware of a bunch of Kuiper objects, and those unknown objects might be exerting their influence, and (3) we haven't actually seen P9 yet, visually, so skepticism is healthy until then.
Yes, thank you. It's been a while since I've watched the video, so calling it "opposing arguments" was a stretch. More like a healthy dose of skepticism.
Pretty sure the orbit of Pluto has been well-known for some time now.
Say there is a planet out there, might it have a protective effect from things hitting earth, similar to how Jupiter is said to help reduce the chances of things hitting earth? Maybe it's too far away, but multi-body dynamics is complicated! Considering the previous lizard 'lords' of-the-earth for millions of years seem to have been largely ended by such a collision, maybe there's more we should be doing to detect and prepare for such an event?
Seems like a perfect test for the Titius-Bode-Blagg law (https://en.wikipedia.org/wiki/Titius%E2%80%93Bode_law).
(No, not the original Bode's Law, which was just a first approximation! Mathematician Mary Blagg did the real work in the early 20th century, but was mostly unacknowledged until nearly 70 years later.)
It works, not just for the solar system, but also for the satellite systems of Jupiter and Saturn; but no one knows precisely why...
(No, not the original Bode's Law, which was just a first approximation! Mathematician Mary Blagg did the real work in the early 20th century, but was mostly unacknowledged until nearly 70 years later.)
It works, not just for the solar system, but also for the satellite systems of Jupiter and Saturn; but no one knows precisely why...
Do they give the odds of the null hypothesis? i.e. that there is no planetary mass object out there.
"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