‘Goblin’ world found orbiting at the edges of the Solar System
nature.com
nature.com
The amount of sky we have to look for Planet IX is enormous (and given how faint it is likely to be), and the evidence so consists of about ten of these TNOs with these orbits (not many, but it's very hard to make these orbits). But there are potentially hundreds of bodies with orbits like these waiting to be found by a the soon to be constructed LSST, which is an 8 meter telescope that will survey its entire sky every 3 days. With many more of these orbits to predict from, we may really narrow down the search space to look for it, and ultimately test its existence.
[1] Predicted by Konstantin Batygin and Mike Brown, the latter of which played a big part in helping to disqualify Pluto as a planet by discovering Eris. I know from a lunch-talk that he greatly relishs the thought of both demoting the former Planet XI and predicting the new one.
To get a significant inclination (ie away from the low inclinations of the inner planets) and a drop in the perihelion (ie highly oval rather than the round orbits of the inner planets) you need a close pass of a large body. As the little think comes close to the big thing it is thrown randomly, away from the nicely round orbits of most things in the early solar system. So if you find a body with those two features, you know it passed close to something big somewhere our near the highest part of its orbit. That is the evidence of a large object out beyond pluto.
The clustering of the arguments of perihelia is less straight forward (you can see it in Figure 4 of the linked pre-print PDF in another comment) and my limited understanding is that they are shepherded into that configuration over time by the large body. That is more clear when you see the results of the numerical simulations I suppose.
The paper authors are actually arguing for a Planet X which has had periodic encounters much weaker than that at a distance of a few hundred au.
It's orbital eccentricity is ~0.94!
Inclination of 11.669 degrees
The diameter listed in the paper is 300km assuming a moderate albedo of 15%.
The paper suggested this object provides more evidence of the existence of Planet X/IX hypotheses of the authors (Trujillo/Shepard/et.al.) and Brown/Batygin.
Every now and again, my intuition breaks utterly down.
Special cases like the infrared spectrum (JWT) exist. But the delays show how extremely difficult space based observation is.
[0] https://en.wikipedia.org/wiki/Adaptive_optics
[Edit: wrong link]
The authors had this to say about it:
Surprisingly, like 2012 VP113, 2015 TG387 is relatively bright compared to the limiting magnitude of most of the survey fields. The Subaru observations generally go deeper than 25.5 mags, making 2015 TG387 about 1.5 mags brighter than the limiting magnitude of the disocovery survey fields it was found in.
It always struck me as a really nice response to anyone being silly about fake landings.
https://www.nasa.gov/mission_pages/LRO/news/apollo-sites.htm...
Given the etymology of that word, that's a deliciously ironic sentence :)
"Fuck you beliefs" are a personal theory of mine. People sometimes assume ridiculous and deliberately provocative "beliefs" as a means of explicit rejection of a social order. The canonical example would be Satanism as a rejection of Christian culture/society. Believing Apollo is a hoax or that the Earth is flat is an explicit rejection of the industrial/scientific/corporate/university complex and its culture. The absurdity of these beliefs adds to their value as acts of protest. The phenomenon can also take the form of refusal to believe something taught by the hated authority. If the belief being refused is actually true and demonstrably so, it becomes a more potent act of protest.
Talk to the people that hold beliefs like the Apollo hoax and scratch the surface and you'll usually find someone who is under-employed in a dead-end job with no future and too much student loan debt. They are adopting an absurdist epistemology in protest of a society that they see as having failed them.
When I see conspiracy theories becoming popular I see a metaphysical and epistemological version of people throwing Molotov cocktails in the street at cops in riot gear under clouds of tear gas. Maybe this is what mass protests and "riots in the street" look like in the Information Age.
Maybe they should do actual protests and "riots in the street" then, instead of trying their best to be tagged as loonies :^).
NOTE: these were taken from lunar orbit, not earth-based telescopes.
(shadow) https://www.space.com/6997-photos-reveal-apollo-11-moon-land...
(large-ish, descent stage, rover tracks) https://www.nasa.gov/sites/default/files/images/584392main_M...
It's really hard to estimate how long the hardware might last. Obviously there's no air or water, but there will be damage from radiation, temperature cycling, and micrometeorite abrasion.
A wild guess would be a similar timescale - max 100 million years, at which point there will be small anomalous piles of metal dust left, but no visible structure.
(But that's just a guess, and could be way out.)
https://www.reddit.com/r/askscience/comments/2n6zo0/comment/...
I would usually expect 2^3 to mean 8, and 2^^3 to mean 16
Perhaps too much time reading people talk about 3^^^^3 dust specs
I'm duty-bound to point out that this is only true in a philosophical, interpretive sense based on the aesthetics of explanations. Scientifically it's completely understood.
Science is just a way of compressing what we perceive with our senses into compact descriptions that our easy to memorize and understand by human beings. That is all. In the words of Neil Bohr, "Physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods of ordering and surveying human experience.".
I don't think this is true. The axioms can be testable, in which case you can do a little better than faith and say that "well, this is how it seems to work." For example I could have a theory that when I press the gas pedal my car moves forwards. Later on I could discover another theory that explains why that theory is true, but in the meantime I'm better than faith but worse than complete fundamental knowledge. That's where physics is - if we had complete fundamental knowledge many of us would go home, having nothing left to do.
But I'm pretty sure even in rational numbers probability would be exactly zero, because that's how probability there is defined (as a limit of a sequence, and limit is zero).
P (X | X) = 1.
And it's a really sorry state of affairs for photons that their vacations pass instantaneously.
(IOW: I was poking fun at the OPs statements of the photon travelling "possibly weeks", not making a statement of fact. I thought the "beaches of Neptune" bit gave it away, but I guess not)
I don't think the suggestion is that this object is planet IX, it's that this object provides evidence that there may be some other planet IX out there.
A rogue planet orbiting a galactic core, or massive BH, would still be called a planet despite in no way clearing its orbit of anything.
https://www.konstantinbatygin.com/about-me/
Here's a band photo (Chaz is on the right): https://static1.squarespace.com/static/587e9fe446c3c40b37290...
I also wondered if it was representative of a class of Goblin objects. I guess the discoverers just liked 'goblin' as a term for something that stays in the dark.
It's interesting to see how new objects are named: https://www.minorplanetcenter.net/iau/info/OldDesDoc.html
So... every year in August astronomers discover a lot of "The Goblins ;-)".
A short article, but in some ways more details. And some links
Kuiper belt and Oort cloud are well-known decades-old terms
As for the rest of the terms, they are new to me due to my non-familiarity with cosmology in general.
It's also unclear to me if the Goblin orbits in the usual planetary plane.
> A proposal before the International Astronomical Union for the definition of a planet would have defined a planet as "a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid-body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet"[2].
[1] https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)
[2] https://www.webcitation.org/62D6DNhLH?url=http://www.iau.org...
In general, while total angular momentum is conserved, rigid bodies tend to rotate in an unstable fashion, because rigid-body forces apply different amounts of torque to different parts of the object. Which I kind of knew about but I didn't connect the dots. Hence no constant speed and angular direction, and no hydrostatic equilibrium. That was the missing link for me!
So, flow velocity is simply the fluid mechanical velocity vector field/mapping. And it has to be constant, otherwise the object would not be in equilibrium, but it'd be still flowing (as in it would have parts that are going somewhere).
Now I think this definition you have found is not directly applicable to rotating celestial bodies, as the point velocity is a vector, and it constantly changes due to the rotation.
So probably a higher order derivative is zero, and that's the condition that we should use.
Or of course we can transform to a non rotating frame.
But what the parent poster said confuses me: "a velocity that may be changing, but the change in velocity with position is smooth, or the object would be ripping itself apart. This means the object has flow." You can have smooth and constant rotation but with many axes (tumbling), so I don't really see how this gets us to roundisness.
As I understand the concept, the point is that "the object doesn't have parts that want to fall toward its center of gravity, but can't because rigid forces", because it's big enough that gravity creates enough pressure and heat that everything becomes plastic over thousands of years, and thus flows. (But this doesn't make much sense, because cold enough rock is pretty stable - as far as I know - so the material will only allow gravity to overcome it if it undergoes enough crystal structure faults [due to radioactive decay or exogenous damage, such as micrometeorites] - so the flow rate is constant, zero, even if there are stresses and forces that would increase the flow.)
[0] https://news.ycombinator.com/item?id=18120244 [1] Ref. this table: https://en.wikipedia.org/wiki/Orbital_inclination#Observatio...
Poor Pluto...
Maybe i'm way off here, the government mind control satellites seem to have got to my reviewers.
I think the planet X moniker originally meant 'x' as unknown (it was coined during the search that found Pluto). Nowadays, it has been used to refer to several distinct theories including Planet IX. I dunno when exactly the X got re-interpreted.
What I do know is WE'RE DOOOOMED! (according to the internet).