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Title: Why did Earth retain most of its water while Venus and Mars lost theirs? Post by: ppk on May 3, 2012 Why did Earth retain most of its water while Venus and Mars lost theirs?
Title: Re: Why did Earth retain most of its water while Venus and Mars lost theirs? Post by: lewis on May 6, 2012 The basic answer is that Earth was at just the right distance to retain water as liquid. Venus lost its water because it was too hot. At its closer proximity to the Sun, Venus was warm enough to keep all its water in gaseous form in the atmosphere. When the runaway greenhouse effect became prominent, Venus became even warmer and the water vapor escaped into space. Mars was far enough from the Sun that it was cold enough for the water vapor to freeze out of the atmosphere, resulting in thick polar caps.
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