Space Is Full of Planets, and Most of Them Don't Even Have Stars

Re:Space Is Full of Planets, and Most of Them Don't Even Hav... by zeth___ on Wednesday May 30, 2018 @05:17AM (#17186244)

Life shows up in the fossil record more or less as soon as rocks on the Earths surface start forming.

The first billions years on earth mostly involved the planet getting hit by large things and the surface melting. Repeat every millennium.

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Re:Space Is Full of Planets, and Most of Them Don't Even Hav... by throwaway5752 on Wednesday May 30, 2018 @08:29AM (#17187118)

You just explained why there's no fossil record from early earth, unless I'm misunderstanding you and that was your point.

Ocean floor is continuously destroyed as it's subducted, and continents won't have fossils if they are under frequent bombardment.

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Re:Space Is Full of Planets, and Most of Them Don't Even Hav... by joshuahedlund on Wednesday May 30, 2018 @10:09AM (#17187740)

> continents won't have fossils if they are under frequent bombardment.

Right, but if giant bombardments completely boil away the oceans and atmosphere to rain liquid rocks back down on the surface, there very very likely won't be life, either. So the claim is not just that "fossils only go back to X" but that X is so close to the end of the giant bombardments that there's almost no time left (geologically speaking - maybe 10-20MY) for "life but no fossils yet".

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