# The Age of Planet X! **URL:** \ **Category:** Factual Questions\ **Created:** [January 20, 2016, 5:23pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687 "2016-01-20T17:23:37Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [January 22, 2016, 5:08pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/41 "2016-01-22T17:08:55Z")
> [@Chronos](#): > > We have never detected any evidence for a planet in another galaxy, and such a feat is insanely beyond our technological capabilities. Well, unless we get lucky: [http://news.softpedia.com/news/First-Exoplanet-in-Another-Galaxy-Found-113678.shtml](http://news.softpedia.com/news/First-Exoplanet-in-Another-Galaxy-Found-113678.shtml) > **[First extragalactic exoplanet may have been found](https://www.newscientist.com/article/dn17287-first-extragalactic-exoplanet-may-have-been-found/)** > > More than 350 extrasolar planets have been discovered, but all lie in the Milky Way – a new simulation bolsters the case that a planet may have been detected in the nearby Andromeda galaxy > **[Extragalactic planet](https://en.wikipedia.org/wiki/Extragalactic_planet)** > > An extragalactic planet, also known as an extragalactic exoplanet or an extroplanet, is a star-bound planet or rogue planet located outside of the Milky Way Galaxy. Due to the immense distances to such worlds, they would be very hard to detect directly. However, indirect evidence suggests that such planets exist. Nonetheless, the most distant known planets are SWEEPS-11 and SWEEPS-04, located in Sagittarius, approximately 27,710 light-years from the Sun, while the Milky Way is a A microlensing ev... ---
**Author:** ![Jonathan\_Chance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jonathan_chance/32/701_2.png) [@Jonathan\_Chance](https://boards.straightdope.com/u/Jonathan_Chance)\ **Post date:** [January 22, 2016, 7:01pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/42 "2016-01-22T19:01:05Z")
Very informative but more GQ. Let me move it there. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 22, 2016, 7:25pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/43 "2016-01-22T19:25:24Z")
That’s a one-time event. One explanation, and perhaps the most likely one, is that it was microlensing caused by a planet, but I’d want to see periodicity (which we’re almost certainly not going to get) before I’d call it a discovery of a planet. As it is, even if a planet is the most likely explanations, there are enough other explanations that it being a planet is probably still less than 50% probable. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [January 22, 2016, 7:27pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/44 "2016-01-22T19:27:31Z")
> [@Malden\_Capell](#): > > Isn’t this how Neptune was eventually found - irregularities in Uranus’ orbit explained by another large planet further away? Yes. It’s also how Pluto was found. And, additionally, why Pluto was considered much bigger than it is when it was discovered, and also why it was almost immediately granted planethood. Turns out that Pluto is much too small to cause the observed perturbations in Neptune’s orbit. But Pluto happened to be there where they expected the big unknown planet to be, so the initial assumption was that Pluto _was_ the big unknown planet. It took a long time to realize it was actually tiny, and I think the idea was that the Oort cloud and Kuiper belt objects would replace Pluto as the theoretical cause of Neptune’s orbital anomalies. I’m not sure if new data has prompted this speculation about another planet, or if it’s the same old “Planet X” fad that comes back every ten years or so. ---
**Author:** ![Find\_Friends](https://avatars.discourse-cdn.com/v4/letter/f/c37758/32.png) [@Find\_Friends](https://boards.straightdope.com/u/Find_Friends)\ **Post date:** [January 22, 2016, 7:57pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/45 "2016-01-22T19:57:37Z")
Name for the new planet, if found? Why, Ceciladams, of course! ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [January 22, 2016, 9:35pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/46 "2016-01-22T21:35:38Z")
**Yuggoth! Yuggoth!** They have to name it **Yuggoth!** ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 22, 2016, 10:12pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/47 "2016-01-22T22:12:43Z")
Closely related but less serious thread: [What should we call the new ninth planet? - In My Humble Opinion - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=781612) ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [January 22, 2016, 10:42pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/48 "2016-01-22T22:42:32Z")
There seems to be a real push to grant this thing official planethood, assuming it’s found, on the basis that if the predictions are correct it would be massive and gravitationally dominant. But it’s already surmised that it would have an eccentric elliptical orbit and perhaps one that’s significantly out of the plane of the eight real planets, which suggests a different origin than the other planets. Wouldn’t it make more sense to consider it a kind of distant Kuiper Belt Object rather than a real planet? ---
**Author:** ![Don\_t\_Panic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/don_t_panic/32/398_2.png) [@Don\_t\_Panic](https://boards.straightdope.com/u/Don_t_Panic)\ **Post date:** [January 22, 2016, 11:10pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/49 "2016-01-22T23:10:46Z")
> [@teflon\_grut](#): > > … or Planet 9, or Planet Nine, or whatever you want to call it. Planet Nine from outer space. Yes, I did think of that all by myself. Only to discover that the rest of the internet, obviously, was already all over it. ---
**Author:** ![Nansbread1](https://avatars.discourse-cdn.com/v4/letter/n/6a8cbe/32.png) [@Nansbread1](https://boards.straightdope.com/u/Nansbread1)\ **Post date:** [January 23, 2016, 12:09am UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/50 "2016-01-23T00:09:34Z")
Why did they not call it Nibiru then? ---
**Author:** ![simster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/simster/32/1047_2.png) [@simster](https://boards.straightdope.com/u/simster)\ **Post date:** [January 23, 2016, 1:46am UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/51 "2016-01-23T01:46:09Z")
> [@Martian Bigfoot](#): > > Planet Nine from outer space. It’s not from outer space - its in outer space. If it was from, I’m sure we’d all be screaming in panic by now. ---
**Author:** ![Bruce\_Wayne](https://avatars.discourse-cdn.com/v4/letter/b/22d042/32.png) [@Bruce\_Wayne](https://boards.straightdope.com/u/Bruce_Wayne)\ **Post date:** [January 23, 2016, 2:44am UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/52 "2016-01-23T02:44:42Z")
Science Friday on NPR had on the guys on who discovered it. They seems confident that it would be discovered within 5 years. They also noted that astronomers they know that were looking at certain regions of the sky are now reviewing their old data to see if they may have already taken a picture of it without realizing it. According to to them planet 9 is at its farthest from the sun and if it was visible, it would be so during a November evening. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 23, 2016, 2:55am UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/53 "2016-01-23T02:55:28Z")
> [@Derleth](#): > > You can figure out [Jupiter]‘s not a star because it moves relative to the stars, but you need multiple nights’ worth of observing just to get that much information. Just a couple nitpicks here. Actually planets are distinct from stars in that they don’t twinkle nearly as much. Stars are point sources of light, so any small variation in the atmosphere along their sight path will cause a twinkle. With planets, you can see their disk, so it takes a larger amount of atmospheric disturbance to cause them to twinkle. > [@](#): > > You certainly can’t see any of [Jupiter’s] moons without help. That’s only because Jupiter is so bright. The Galilean moons are bright enough to be naked-eye objects. In fact they’re brighter than Uranus. [insert mooning joke here] > [@DrCube](#): > > I’m not sure if new data has prompted this speculation about another planet, or if it’s the same old “Planet X” fad that comes back every ten years or so. It’s mostly computer modelling based on the orbits of a half dozen or so of the most distant TNOs (which are called sednoids). It could be that the next sednoid or two discovered will not have a perihelion in the right range and totally trash this theory. ---
**Author:** ![Peremensoe](https://avatars.discourse-cdn.com/v4/letter/p/ce7236/32.png) [@Peremensoe](https://boards.straightdope.com/u/Peremensoe)\ **Post date:** [January 23, 2016, 3:30am UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/54 "2016-01-23T03:30:31Z")
> [@wolfpup](#): > > There seems to be a real push to grant this thing official planethood, assuming it’s found, on the basis that if the predictions are correct it would be massive and gravitationally dominant. But it’s already surmised that it would have an eccentric elliptical orbit and perhaps one that’s significantly out of the plane of the eight real planets, which suggests a different origin than the other planets. Wouldn’t it make more sense to consider it a kind of distant Kuiper Belt Object rather than a real planet? Planet Nine is postulated to be well beyond the Kuiper Belt, in the extreme range of the “scattered disk,” or the “detached” objects. When the definition of planets was thrashed out a few years ago, nobody thought to put anything in there about inclination, or origin. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 23, 2016, 4:05pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/55 "2016-01-23T16:05:43Z")
On the other hand, one can make a case that it hasn’t “cleared its orbit”, since its orbit covers such a vast amount of space, and the miscellaneous other junk in it, when added up, probably outmasses it by a considerable margin. So we could end up with the absurdity of a “dwarf planet” ten times the size of Earth. ---
**Author:** ![Peremensoe](https://avatars.discourse-cdn.com/v4/letter/p/ce7236/32.png) [@Peremensoe](https://boards.straightdope.com/u/Peremensoe)\ **Post date:** [January 23, 2016, 4:13pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/56 "2016-01-23T16:13:36Z")
> [@Chronos](#): > > On the other hand, one can make a case that it hasn’t “cleared its orbit”, since its orbit covers such a vast amount of space, and the miscellaneous other junk in it, when added up, probably outmasses it by a considerable margin. I don’t know how we could make either that case, or the converse, with rigor. ---
**Author:** ![Munch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/munch/32/5281_2.png) [@Munch](https://boards.straightdope.com/u/Munch)\ **Post date:** [January 23, 2016, 4:35pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/57 "2016-01-23T16:35:54Z")
> [@Nansbread1](#): > > Why did they not call it Nibiru then? For one, because it still hasn’t been found. ---
**Author:** ![Stately\_Greek\_Automaton](https://avatars.discourse-cdn.com/v4/letter/s/aca169/32.png) [@Stately\_Greek\_Automaton](https://boards.straightdope.com/u/Stately_Greek_Automaton)\ **Post date:** [January 29, 2016, 4:21pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/58 "2016-01-29T16:21:52Z")
> [@Peremensoe](#): > > All the exoplanets astronomers have identified are ~much~ closer to their suns than the postulated Planet Nine is to ours. [Not necessarily](https://www.inverse.com/article/10573-free-floating-planet-turns-out-to-have-million-year-orbit). It’s just that most of our methods for planet hunting tend to work better for planets that are closer to their respective stars. ---
**Author:** ![Totenfeier](https://avatars.discourse-cdn.com/v4/letter/t/4bbf92/32.png) [@Totenfeier](https://boards.straightdope.com/u/Totenfeier)\ **Post date:** [January 29, 2016, 4:46pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/59 "2016-01-29T16:46:29Z")
> [@BrainGlutton](#): > > **Yuggoth! Yuggoth!** They have to name it **Yuggoth!** Ia(umlaut)! Ia(umlaut)! ---
**Author:** ![Totenfeier](https://avatars.discourse-cdn.com/v4/letter/t/4bbf92/32.png) [@Totenfeier](https://boards.straightdope.com/u/Totenfeier)\ **Post date:** [January 29, 2016, 4:49pm UTC](https://boards.straightdope.com/t/the-age-of-planet-x/743687/60 "2016-01-29T16:49:10Z")
Um…that’s real little because…I’m worshipping all the way from Earth! Yeah…that’s the ticket! [Previous page](https://boards.straightdope.com/t/the-age-of-planet-x/743687.md?page=2) [Next page](https://boards.straightdope.com/t/the-age-of-planet-x/743687.md?page=4)