Evolution of the early Earth

The faint early Sun paradox refers to the fact that our understanding of stellar evolution suggests that stars get more luminous over time.

This implies that the temperature on the Earth was quite a bit cooler 4 billion years ago than it is now. Among other things, this might cause a problem for the origin of life -- we need that Solar energy to get things going.

There is more specific contradictions which are so strong that people sometimes refer to the faint early Sun paradox.

Three lines of evidence that suggest it was warmer on Earth -- and Mars -- in the past are these:

  • geologic evidence on Earth
  • atmospheric evidence on Earth
  • geologic evidence on Mars

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