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That’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 cryo

That’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 ago
My understanding is that this is most likely a gas planet, not a rocky one.
- dr_zoidberg 9y ago
  An ice giant, like Uranus and Neptune.
- otp124 9y ago
  Why would it be gaseous if Pluto is rocky? Is it the size?
  - dr_zoidberg 9y ago
    I'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.
    - sulam 9y ago
      I’m suspicious about one statement you’ve made here. Either you haven’t made it precisely, or it may not logically follow. We’ve observed many super earths because that is what we can observe. The sensitivity of our instruments make it hard to observe Earth-like planets unless they are at Mercury-type orbital distance or even closer. There are some recent counter-examples, but to say that these are the most common because that’s what we’ve been able to observe is a selection bias of the first order. Now, perhaps planetary formation models predict many closely orbiting Neptune class planets, and independently observations are demonstrating that this is true. That would be a stronger statement, although still perhaps somewhat driven by observational data, since any model which doesn’t predict this might be kicked to the curb by now.
      - dr_zoidberg 9y ago
        Yes, I see your point. Basically I mentioned the Kepler mission results, without providing the relevant link[0]. Right there you can see that super-earths are quite high in frequency. However, I remember a talk held sometime last year (or maybe this year) where the mission team talked about the Kepler results and they specifically said that super-earths were now the most common planet type found. But I can't find it, and can't back that up with a strong source. What's more, looking at the published results[1], gas giants are far more frequent (and that would line up with the selection bias you noted). The only thing I can think that would back the claim about super-earths, would be considering them on radius alone, in which case yes, the 2 < R ≤ 6 R_Earth class is the most common class[1]. Edit: I was looking mainly at the mass results (in which case a SE is any planet between 2-10x Earths mass), not the radius results. But then, the definition is still a bit shaky, with different criteria[2]. [0] https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 [1] https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail.html https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail... [2] https://en.wikipedia.org/wiki/Super-Earth#Definition https://en.wikipedia.org/wiki/Super-Earth#Definition
- deleted 9y ago
  [deleted]
- QAPereo 9y ago
  https://en.m.wikipedia.org/wiki/Planet_Nine#Size_and_composition https://en.m.wikipedia.org/wiki/Planet_Nine#Size_and_composi... https://en.m.wikipedia.org/wiki/Ice_giant https://en.m.wikipedia.org/wiki/Ice_giant More like a giant lump of ice and rock with a frozen atmosphere, a so-called “Ice Giant” like Neptune or Uranus.
mrfusion 9y ago
What if it’s highly geoactive from being so big? What if it had a nice atmosphere and was 70 degrees?
- QAPereo 9y ago
  You can’t really have a nice atmosphere with so little incoming solar radiation, and at 10g you’d be talking about a truly THICK atmosphere. Moons though, could be “squeezed and stretched” from the gravitational interaction with the planet, but again they’d be coooooold. You’d have activity, but probably cryogenic volcanoes and the like.
  - kijin 9y ago
    Surface gravity on a planet with 10 times the mass of Earth will not be 10g. The increased radius alone will reduce the surface gravity by a factor of 2 at least. But Planet 9 is also likely to be much less dense than Earth. Earth is the densest object in the solar system. You can't match our iron core with materials available in the outer reaches, so the surface will be even further away from the center. Surface gravity on Saturn is just around 1g (for a suitable definition of "surface"). Uranus is 0.9g. Neptune is 1.1g. Planet 9 is likely to be in the same ballpark if it's an ice giant.
    - QAPereo 9y ago
      You’ve confused radius and mass. 10x mass = 10x gravity, and then radius is a totally separate issue. Mass and surface gravity are proportional, while radius depends on issues of composition.
      - kijin 9y ago
        Surface gravity absolutely depends on the radius. Gravitational force is proportional to mass and inversely proportional to the square of distance. Radius is the distance between the center of a planet and its surface. If this sounds wrong, please see the Wikipedia page for Saturn and explain how a planet with 95 times the mass of Earth is listed as having a surface gravity of only 1.065 g. (Actually, I was wrong above: the increased radius alone would reduce the surface gravity of this hypothetical planet by a factor of 4.6, not just 2, assuming Earth-like density.)

IAmGraydon 9y ago

My understanding is that this is most likely a gas planet, not a rocky one.

dr_zoidberg 9y ago
An ice giant, like Uranus and Neptune.
otp124 9y ago
Why would it be gaseous if Pluto is rocky? Is it the size?
- dr_zoidberg 9y ago
  I'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.
  - sulam 9y ago
    I’m suspicious about one statement you’ve made here. Either you haven’t made it precisely, or it may not logically follow. We’ve observed many super earths because that is what we can observe. The sensitivity of our instruments make it hard to observe Earth-like planets unless they are at Mercury-type orbital distance or even closer. There are some recent counter-examples, but to say that these are the most common because that’s what we’ve been able to observe is a selection bias of the first order. Now, perhaps planetary formation models predict many closely orbiting Neptune class planets, and independently observations are demonstrating that this is true. That would be a stronger statement, although still perhaps somewhat driven by observational data, since any model which doesn’t predict this might be kicked to the curb by now.
    - dr_zoidberg 9y ago
      Yes, I see your point. Basically I mentioned the Kepler mission results, without providing the relevant link[0]. Right there you can see that super-earths are quite high in frequency. However, I remember a talk held sometime last year (or maybe this year) where the mission team talked about the Kepler results and they specifically said that super-earths were now the most common planet type found. But I can't find it, and can't back that up with a strong source. What's more, looking at the published results[1], gas giants are far more frequent (and that would line up with the selection bias you noted). The only thing I can think that would back the claim about super-earths, would be considering them on radius alone, in which case yes, the 2 < R ≤ 6 R_Earth class is the most common class[1]. Edit: I was looking mainly at the mass results (in which case a SE is any planet between 2-10x Earths mass), not the radius results. But then, the definition is still a bit shaky, with different criteria[2]. [0] https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 https://en.wikipedia.org/wiki/Kepler_(spacecraft)#2011 [1] https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail.html https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail... [2] https://en.wikipedia.org/wiki/Super-Earth#Definition https://en.wikipedia.org/wiki/Super-Earth#Definition
deleted 9y ago
[deleted]
QAPereo 9y ago
https://en.m.wikipedia.org/wiki/Planet_Nine#Size_and_composition https://en.m.wikipedia.org/wiki/Planet_Nine#Size_and_composi... https://en.m.wikipedia.org/wiki/Ice_giant https://en.m.wikipedia.org/wiki/Ice_giant More like a giant lump of ice and rock with a frozen atmosphere, a so-called “Ice Giant” like Neptune or Uranus.

mrfusion 9y ago

What if it’s highly geoactive from being so big? What if it had a nice atmosphere and was 70 degrees?

QAPereo 9y ago
You can’t really have a nice atmosphere with so little incoming solar radiation, and at 10g you’d be talking about a truly THICK atmosphere. Moons though, could be “squeezed and stretched” from the gravitational interaction with the planet, but again they’d be coooooold. You’d have activity, but probably cryogenic volcanoes and the like.
- kijin 9y ago
  Surface gravity on a planet with 10 times the mass of Earth will not be 10g. The increased radius alone will reduce the surface gravity by a factor of 2 at least. But Planet 9 is also likely to be much less dense than Earth. Earth is the densest object in the solar system. You can't match our iron core with materials available in the outer reaches, so the surface will be even further away from the center. Surface gravity on Saturn is just around 1g (for a suitable definition of "surface"). Uranus is 0.9g. Neptune is 1.1g. Planet 9 is likely to be in the same ballpark if it's an ice giant.
  - QAPereo 9y ago
    You’ve confused radius and mass. 10x mass = 10x gravity, and then radius is a totally separate issue. Mass and surface gravity are proportional, while radius depends on issues of composition.
    - kijin 9y ago
      Surface gravity absolutely depends on the radius. Gravitational force is proportional to mass and inversely proportional to the square of distance. Radius is the distance between the center of a planet and its surface. If this sounds wrong, please see the Wikipedia page for Saturn and explain how a planet with 95 times the mass of Earth is listed as having a surface gravity of only 1.065 g. (Actually, I was wrong above: the increased radius alone would reduce the surface gravity of this hypothetical planet by a factor of 4.6, not just 2, assuming Earth-like density.)