More than three-quarters of the planet candidates discovered by NASA's Kepler spacecraft have sizes ranging from that of Earth to that of Neptune, which is nearly four times as big as Earth. Such planets dominate the galactic census but are not represented in our own solar system. Astronomers don't know how they form or if they are made of rock, water or gas.
Fuente : http://feeds.sciencedaily.com/~r/sciencedaily/~3/O...
Fuente : http://feeds.sciencedaily.com/~r/sciencedaily/~3/O...