I've watched documentaries about the solar system, where it is suggested that Venus once had oceans of liquid water similar to those that cover most of Earth today. Venus is now in a period of runaway greenhouse effect and has lost its oceans.
I've always wondered whether the apparent overabundance of water on Earth could be partially explained by our planet sweeping up the water, pushed into Earth's path by the solar wind, after it had been liberated from Venus. I know one theory on where our water came from is a bombardment of comets - but I've always wondered whether some could also have arrived after Venus heated up.
How stupid is this as an idea?
10/12/2014 - article from the bbc - Rosetta results: Comets 'did not bring water to Earth'
20/09/2017 - article from www.spacetelescope.org - Hubble discovers a unique type of object in the Solar System which includes an interesting note - " Current research indicates that water came to Earth not via comets, as long thought, but via icy asteroids."