for National Geographic News
The first known planet beyond the solar system that could harbor life as we know it has been discovered, scientists report.
The most Earthlike planet yet found, it orbits a red dwarf star and likely contains liquid water, said the European astronomers who made the discovery.
The planet is estimated to be only 50 percent larger than Earth, making it the smallest planet yet found outside the solar system, according to a team led by Stephane Udry of the Geneva Observatory in Switzerland.
Known as Gliese 581 c, the newfound world is located in the constellation Libra, some 20.5 light-years away.
The planet is named after the red dwarf star it orbits, Gliese 581, which is among the hundred closest stars to Earth.
Because the planet is 14 times nearer to its star than Earth is to the sun, a year there lasts just 13 days. Gravity on the planet's surface, though, may be twice as strong as Earth's gravity.
Despite the close proximity to its parent star, however, Gliese 581 c lies within the relatively cool habitable zone of its solar system. That's because red dwarfs are relatively small and dim, and are cooler than our sun, the team explained.
The scientists estimated the planet's surface temperature at between 32 and 104 degrees Fahrenheit (0 and 40 degrees Celsius).
"This means water can exist in liquid form," Udry said. "If you want life like our own, then you need water."
The team reports its findings in the journal Astronomy and Astrophysics.
Rock or Oceans
The new world could feature familiar, rocky terrains or be completely covered with oceans, the researchers said.
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