Why is the Earth's early atmosphere thought to have resembled the atmospheres of Mars and Venus today?

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Question

Why is the Earth's early atmosphere thought to have resembled the atmospheres of Mars and Venus today?

Accepted Answer

Those atmospheres are mainly carbon dioxide, as the early Earth's is believed to have been — Award 1 mark. Neither planet developed life that could photosynthesise, so neither lost its carbon dioxide the way the Earth did.

Answer

Those atmospheres are mainly carbon dioxide, as the early Earth's is believed to have been

Answer

Those planets have liquid oceans like the early Earth

Answer

Photosynthesis takes place on both of those planets

Answer

Those atmospheres are mainly nitrogen

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