Japanese scientists proposed a new classification scheme for terrestrial planets: Type I planets, whose magma oceans solidified quickly and retain more water, and Type II, which had a magma ocean for ... more 
Japanese scientists proposed a new classification scheme for terrestrial planets: Type I planets, whose magma oceans solidified quickly and retain more water, and Type II, which had a magma ocean for as long as 100 million years. less 
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SPACE.com | Photo By © Keiko Hamano
Wed, May 29, 2013 1:15 PM EDT