The continental plates that slide along Earth's surface can be destructive. Their motions -- known as plate tectonics -- create volcanoes, earthquakes, and other violent events. Yet without them, life on our planet might not exist. They recycle carbon dioxide into the atmosphere, keeping us warm. And they help produce the chemistry of life.
Researchers from Harvard recently concluded that if Earth had been born much smaller, though, it might not have been able to drive tectonics. The planet would have radiated away the heat that drives tectonics, and the crust would have frozen in place -- like Venus and Mars.
So as astronomers look for good homes for life in other star systems, they might want to concentrate their efforts on "super-Earths" -- rocky planets that are more massive than Earth. According to the researchers, these worlds would have plenty of internal heat to drive plate tectonics, providing many of the conditions needed for life.
Astronomers have discovered several super-Earths orbiting other stars. But most of them aren't at the right distance from their stars to have liquid water, which is an essential ingredient for life.
Over the coming decades, though, astronomers expect to find hundreds of these planets, and maybe more. They'll also develop the tools to scan their atmospheres for signs of life. So they may discover whether super-Earths really are super environments for life.
Script by Damond Benningfield, Copyright 2008
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