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I also don't see how they disprove the contribution of gravity. Remember that Earth is composed of fifty Titan-sized bodies. Titan, and probably Uranus and Nep
by o11c 1y ago
I also don't see how they disprove the contribution of gravity. Remember that Earth is composed of fifty Titan-sized bodies.
Titan, and probably Uranus and Neptune, probably have their methane etc. as a result of outgassing - initially, the volatiles are embedded in the inner rocks, but as they gravitationally differentiate and heat - and are subject to tide-like interactions with other bodies - the volatiles are released.
(The real questions are "Why does Ganymede not have an atmosphere?" and "What's up with Venus, really?")
- andrewflnr 1y agoI believe the idea is that the water was all cooked out of Earth's protoplanetary disk material before it even formed large chunks. So gravity never got a chance to "contribute" on that front.
- o11c 1y agoWell, that seems to make 2 major assumptions (and several minor ones), both of which are probably false: * that the planetesimals that formed Earth had the same orbital characteristics (notably eccentricity), rather than being averaged out. * that planetesimals formed from dust in largely the same manner as planets form from planetesimals
- andrewflnr 1y ago...no, I don't think it makes either of those assumptions.