Celestia Forums

John S. Lewis, Worlds Without End , page 109. I was off, it's actually only three paragraphs! What about gas-giant planets that find themselves in orbits that force unusually high or low temperatures on them? Excursions to lower temperatures will produce bodies with all the chemical simplicity of Ne...

Talking of my Sudarsky giant planets add-on, I may have to add a few bits to it, someone claims that Worlds Without End gives some extra refinements to the scheme, including methane clouds at 50-85K and ammonium hydrosulphide clouds at 150-200K. However I'm going to have to get my hands on a copy b...

Looks like this will be settled soon... at least officially.

http://www.nature.com/news/2005/050801/ ... 801-2.html

Problem with the dynamical clearance criterion is that it doesn't make sense for objects which have been ejected from a solar system, although the fact that they've been ejected suggests they didn't do enough clearance of their region of their original solar system, but what if it is possible to fo...

If people want to collectively call all those things orbiting the Sun or a star 'planets', then if you are going to call Pluto and planet call 2004 MN4 a planet, but don't try and fudge an excuse about why Pluto is a planet and Quaoar is not. But, I'll have to tag that as just my 2 eurocents. I def...

Actually, I don't think so. I think of planetesimals as those things which would in the fullness of time form a planet (given enough material) but didn't, due to lack of time or scattering by other planets. I think that's what Pluto and friends are exactly. The fact that they're round is neither he...

I suspect that the mass/composition levels that lead to gravitational roundness are probably pretty similar to those that would lead to significant interior heating. Perhaps these two definitions are essentially the same, but approaching them from different angles. Though gravitational roundness is ...

Hmm, yes, read that somewhere. It's no good though. Again, it's impractical when it comes to deciding whether a newly discover point-like object or extrasolar 'planet' is a planet. How can you tell it's shape? How can you tell if the heat is from fusion, primordial (Brown Dwarves!), tidal or recent...

I prefer a definition synthesized from those proposed by Stern & Levinson, Buie, Basri, and Brown. That is: planet: an object that orbits a star or stars and is large enough to be shaped primarily by gravity ("rounded") but not large enough to have ever undergone fusion in its interior A planet ...

Request for realistic star glow/flare.jpg colors as described here: http://www.vendian.org/mncharity/dir3/starcolor/ And incidentally, I like having the actual textures all white since that's probably what the eye would see, but having different textures for different classes (to account for e.g. la...

I'm reminded of Triton by these pictures. No cantaloupe terrain, but there are those dark spots/streaks on the lighter areas. Aren't Triton and Titan pretty much identical, other than the obvious size and atmospheric differences?