Finding habitable, Earth-like planets is a Holy Grail of astrobiology. But so far the hunt has been something of a boon and bust.
'Super-Earths'--rocky planets slightly larger than our own--are particularly common outside our Solar System. Some have even been found in the habitable zone--the area around a star where a planet could have liquid water on its surface.
But because of their size, scientists have assumed that super-Earths should be water worlds. Their massive gravity would flatten their topography, letting oceans overflow their basins and inundate the planet.
Now a new study by Nicolas Cowan, at Northwestern University, and Dorian Abbot, at the University of Chicago, suggests this may not be the case.