In the long history of the Earth, was there ever a time when our planet appeared as a predominantly green orb if viewed from outer space? Today, for the most part, the oceans, rivers and lakes appear blue from that same vantage point. Was there a time when algae and the vegetation that took over the continent(s) allowed the Earth to take on a green hue? It seems as if vegetation is always trying to cover something left unattended.
Just like to add another dumb question: If a life sustaining planet is either predominantly blue or green then will it be possible to someday narrow the search for planets that could harbor life by simply figuring out what color they are?