Rocky exoplanets with masses that are between 2–10 times that of the Earth may not have the long periods of volcanic activity that are thought to be essential for life to evolve. That is the conclusion of a new study by scientists in the US and Germany into the rate with which these "super Earths" cool. The research also suggests that understanding the behaviour of a super planet's interior over long periods of time can provide important information about conditions on its surface.
Astronomers have so far found more than 600 super Earths orbiting stars other than the Sun – and many more are expected to be discovered by the Kepler space telescope and other future missions. Super Earths currently offer astronomers the best opportunity to look for signs of extra-terrestrial life because they are easier to find and study with today's telescopes than are Earth-sized exoplanets.
If a super Earth were in the habitable zone of its star – where, in principle, the surface of the planet could be at the right temperature to have liquid water – such an exoplanet could sustain life. Being in the habitable zone alone is, however, not enough because the conditions on the surface of the super Earth must be conducive to life.
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