By Charles Q. Choi
Astrobiology Magazine / Space.com
If not for life, Earth may not have possessed the continents it does now, instead becoming a planet covered nearly entirely in ocean, researchers say.
These new findings suggest that any continents astronomers may one day see on alien worlds may potentially be signs of extraterrestrial life, scientists added.
Earth is currently the only known planet in the universe that has liquid water on its surface. There is life virtually wherever there is liquid water on Earth, so one main focus of the search for extraterrestrial life as we know it is the region around a star where it is neither too hot nor too cold for liquid water to exist on a planet, an area known as the star's habitable zone.
Although water covers most of Earth's surface, nearly 30 percent of the planet is covered by land, sustaining a dazzling variety of life. Scientists might one day be capable of telling if distant planets are similarly covered by land, oceans and clouds by looking for reddish, bluish or grayish tints in the color of those worlds. Researchers have already developed maps of clouds on a giant planet orbiting a distant star. . . .
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