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A possible "Planet Nine" in Earth's solar system would orbit far beyond Neptune
- ComputerGuru 9y agoI thought the presence of a ninth planet that wasn't Pluto was already more-or-less accepted. Here's an article (citing Caltech): http://www.science20.com/news_articles/planet_nine_not_pluto_a_new_planet_discovered_in_our_solar_system-163869 http://www.science20.com/news_articles/planet_nine_not_pluto... > mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles) which is definitely "far beyond Neptune"
- mjw1007 9y agoI think the content of the NASA press release that this article is based on is: - that planet nine theory still seems to be holding up; - Batygin and Brown have just spent a week at Mauna Kea looking for it.
- stephengillie 9y agoIn 12 years, this appears to have regressed from actually seeing the planet, to just a vague theory of its existence. What's going on here? Article from 07/2005[0] where Brown, Trujillo, and Rabinowitz discovered the 10th planet "using the Samuel Oschin Telescope at Palomar Observatory near San Diego. It is currently about 97 times farther from the sun than Earth, or 97 Astronomical Units (AU). For comparison, Pluto is 40 AU from the sun." Article from 01/2015[1] where Brown (and Batygin?) proposed 2 planets might be beyond Pluto's orbit, and cite star HL Tauri, which has a planet forming disk more than 100 AU from the star - supporting the idea of "distant planet formation". Article from 09/2015[2] where Sheppard and Trujillo publish a paper in Nature in 2014. They call it "Planet X". Article from 01/2016[3] where Brown and Batygin proposed the planet in The Astronomical Journal. [0] https://science.nasa.gov/science-news/science-at-nasa/2005/29jul_planetx/ https://science.nasa.gov/science-news/science-at-nasa/2005/2... [1] https://www.universetoday.com/118252/astronomers-are-predicting-at-least-two-more-large-planets-in-the-solar-system/ https://www.universetoday.com/118252/astronomers-are-predict... [2] https://www.washingtonpost.com/news/speaking-of-science/wp/2015/09/03/is-there-a-planet-x-a-massive-perturber-hidden-beyond-pluto/ https://www.washingtonpost.com/news/speaking-of-science/wp/2... [3] https://www.nytimes.com/2016/01/21/science/space/ninth-planet-solar-system-beyond-pluto.html https://www.nytimes.com/2016/01/21/science/space/ninth-plane...
- mjw1007 9y agoThey decided not to classify the 2005 "10th planet" as a planet (and to stop classifying Pluto as one). This new one, if it's there, will be much bigger.
- simcop2387 9y agoAlong with that, the last estimate of it's orbit put it at something like 100-500AU away, which is what it's been so hard to find.
- vladus2000 9y agohttps://en.wikipedia.org/wiki/Eris_(dwarf_planet) https://en.wikipedia.org/wiki/Eris_(dwarf_planet) is likely what the 2005 article is about.
- perseusprime11 9y agoIf Planet 9 theory holds up, then why not Planet 10 and 11 and so forth?
- TomK32 9y agoAs with any system with an unknown, the unknown factor might actually be more than just one factor. Wether Planet 10 is a factor can only be determined once planet 9 is observed proper (so far we only know it has be to "there" but haven't seen it) and measured sufficiently enough to be added to the models of solar system.
- mabbo 9y agoThere's a list of 'weird' things that need to be explained. A big 9th planet orbiting within a fairly tight range of parameters would explain many things on that list. A 10th or 11th planet might also explain it, but not as well, and it's a more complicated answer to have 2 or 3 new planets instead of one. Occam's razor: the simplest explanation is the most likely.
- QAPereo 9y agoThat’s going to be one very rocky, veeeery frozen planet. Still, if it has moons, one of them could be geologically active if the orbit is right. Imagine a cryovolcano erupting, with Sol as a pinprick in the background.
- IAmGraydon 9y agoMy understanding is that this is most likely a gas planet, not a rocky one.
- dr_zoidberg 9y agoAn ice giant, like Uranus and Neptune.
- otp124 9y agoWhy would it be gaseous if Pluto is rocky? Is it the size?
- dr_zoidberg 9y agoI'm not an astronomer, much less planetary scientist[5], but it's got something to do with the size, and location[0]. Rocky planets are suposed to be formed near the star, and the stellar winds "blow" the gaseous elements away from them. The gas giants, like Jupiter and Saturn, form farther away and hence get to hold the more "volatile" elements. Hot jupiters, a class of giants that orbit very close to their stars, are weird and there a two competing hypothsies about their formation[1] so we could say that the precise mechanisms aren't fully understood (but we do have a pretty good idea). As for ice giants, the precise mechanisms for their formation are not completely understood[2]. But what we do know, and it gives a strong(er) foundation for Planet Nine, is that super-earths (or Uranus/Neptune sized planets) are actually the most common type of (exo)planet we've observed so far, and it's a class that's surprisingly missing from our solar system[3] and a "slot" that Planet Nine would fill[4]. [0] https://en.wikipedia.org/wiki/Nebular_hypothesis#Formation_of_planets https://en.wikipedia.org/wiki/Nebular_hypothesis#Formation_o... [1] https://en.wikipedia.org/wiki/Hot_Jupiter#Formation_and_evolution https://en.wikipedia.org/wiki/Hot_Jupiter#Formation_and_evol... [2] https://en.wikipedia.org/wiki/Ice_giant#Formation https://en.wikipedia.org/wiki/Ice_giant#Formation [3] https://en.wikipedia.org/wiki/Super-Earth https://en.wikipedia.org/wiki/Super-Earth [4] https://en.wikipedia.org/wiki/Super-Earth#Planet_Nine https://en.wikipedia.org/wiki/Super-Earth#Planet_Nine [5] I'm a sort of an astronomy geek though, and I pretty much enjoy reading this stuff up until the point I don't understand any more. Which over the years has luckily been moving forward. If you're interested in the subject, follow @plutokiller and @kbatygin on twitter, they're active and link to a lot of articles and their scientific papers.
- ufo 9y agoIts something possible but it isnt guaranteed. There might be other explanations for the unusual orbits of transnetunian objects
- apple4ever 9y agoThere is already a ninth planet- Pluto I believe you mean Planet Ten.
- curtis 9y agoI'm kind of with you on the demotion of Pluto. On the other hand, if we accept Pluto as a planet, then we pretty much have to accept Eris [1] as well, since Eris is more massive than Pluto, making Pluto and Eris the 9th and 10th planets, respectively. So we'd be searching for a possible planet 11. But I guess I'd be OK with that. [1] https://en.wikipedia.org/wiki/Eris_(dwarf_planet) https://en.wikipedia.org/wiki/Eris_(dwarf_planet)
- gweinberg 9y agoYes, I'd call it planet 11. But I'd also call it Goofy. Mother very easily made a jam sandwich using no peanuts, mayonnaise, or glue -> Mercury Venus Earth (asteroids) Mars Jupiter Saturn Uranus Neptune Pluto Mickey and Goofy.
- Razengan 9y agoI reeally would rather not name a major thing like a planet after an American pop culture icon that is barely 100 years old.
- DerekL 9y agoMickey Mouse is only 88 years old.
- freehunter 9y agoWhat's the difference between naming it after a fictional dog vs naming it after a long-forgotten god from a dead religion like other planets? Either way it's a made up pop culture icon that people may or may not understand the reference to. There are many reasons to not want to name a planet "Goofy" that have nothing to do with their relationship to the Disney corporation.
- louithethrid 9y agoWhat if planet nine is a dense cloud of neptune like moons, circling one another?
- maxxxxx 9y agoI think this wouldn't be stable. Either the cloud would fall apart or collapse into something bigger.
- SeoxyS 9y agoWe already have a ninth planet, Pluto. Why did they start calling it a rock again? Isn't the definition of a planet a mostly spherical rock that orbits around a star, no?
- 549362-30499 9y agoNo, by that definition you would have to include a number of other Kuiper belt objects as "planets".
- petascale 9y agoBecause when Pluto was discovered, they thought it was alone out there. Then they found that Pluto was a lot smaller than first thought (mass 1/5th of our Moon, roughly the size of Australia), and that there were a lot of other objects only slightly smaller in similar orbits (the Kuiper belt). And then we found Eris which is just as big as Pluto (slightly smaller in diameter, but more mass). So either they are all planets, potentially thousands of them in the Kuiper belt, or we redefine 'planet' so Pluto, Eris, and similar bodies are excluded. So now a 'planet' is a) orbiting the Sun, b) mostly spherical, and c) mostly alone in its orbital neighborhood[1]. Pluto, Eris et. al are still more than mere rocks, they have been reclassified as dwarf planets[2]. It was a similar story with the asteroid belt: They found the first asteroid (Ceres, I think) and called it a planet. Then they found another, and another, and soon it became clear that there were a very large number of small bodies in similar orbits. So they decided that they weren't planets after all, and called them asteroids instead[3]. The difference with Pluto is just that it happened so recently. [1] https://en.wikipedia.org/wiki/IAU_definition_of_planet https://en.wikipedia.org/wiki/IAU_definition_of_planet [2] https://en.wikipedia.org/wiki/Dwarf_planet#Dwarf_planets_and_possible_dwarf_planets https://en.wikipedia.org/wiki/Dwarf_planet#Dwarf_planets_and... [3] https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)#Classification https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)#Classific...
- SeoxyS 9y agoDoes a planet need to have an active hot core?
- Sniffnoy 9y agoThis article doesn't seem to contain much new. If you read Batygin and Brown's blog, though, you can read more about to what extent they've been able to pin down Planet Nine's location: http://www.findplanetnine.com/2017/09/planet-nine-where-are-you-part-1.html http://www.findplanetnine.com/2017/09/planet-nine-where-are-...
- HocusPocusLocus 9y agoCould we automate the search. Look for portions of the sky where the planet covers a background star. Plot real and false positive data to see what could be there, flying around. Unless it orbits faster than Earth, it's periodic data too. If it does orbit the sun faster than Earth, outside Neptune's orbit, its really cruising!
- dtparr 9y agoFYI, Kepler's 3rd law (the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit) means it'll orbit very slowly (a planet just 100 au out would have nearly a 1000 Earth-year orbit).
- mabbo 9y agoThe problem is that it's a needle in a haystack. Everything in the sky can be thought of in terms of how many degrees or arcseconds wide it is. The moon and sun are nearly the same 'size' in these terms, even though the sun is so much bigger in actual size. This planet 9? It's ten times the size of the Earth (ish), but in terms of arcseconds, it's abysmally tiny. There simply aren't many telescopes powerful enough to see something that small in the sky. Worse, the smaller it is the more places in the sky you need to look to try to find it. It's like you've dropped a single 10nm transistor on your living room carpet.
- WalterBright 9y agoPluto is good enough for me.