A new exoplanet model developed by Nicolas B. Cowan of the Center for Interdisciplinary Exploration and Research in Astrophysics and Dorian Abbot of the University of Chicago, has shown that some "super-earths" may resemble our planet a lot more than previously thought. According to the model, these planets may have oceans and continents.
By definition, a super-earth is more massive than our planet yet less massive than Uranus—or somewhere between 2 and 14 times the mass of the earth. Cowan and Abbott's model of such a planet suggests that more of its water may be tied up in the mantle than previously thought. Where earlier models of super-earths revealed worlds covered with planet-wide oceans, in the new model having less water on the surface means that more land would be visible. This is similar to what has happened here on the earth, where the immense pressures at the bottoms of the oceans forces water deep into the underlying mantle. According to Cowan and Abbot, even if an exoplanet had up to 80 times the amount of water on the earth, there would still be exposed continents.
If this model reflects reality (and as yet no planet has been found that confirms it), then this would be important for the evolution of life on these worlds. As we know from our experience on our our planet, the presence of both continents and oceans is an important driver in a planet's climate and weather systems. The mixture of oceans and land masses also affects in the oceans, which go toward regulating temperatures and distributing nutrients. And the more earth-like conditions may be on an exoplanet, the more likely it is that there may be familiar forms of life.
Art by Ron Miller