Kepler-186f, an Earth-like planet about the size of Earth and located in a part of the universe considered habitable, has been discovered by NASA’s Kepler Telescope, the space agency announced Thursday.
Kepler-186f is the first such planet found in the habitable zone that is near the Earth’s size; most have been 40 percent larger, which makes it more difficult to understand their makeup, a NASA release said.
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"We know of just one planet where life exists — Earth. When we search for life outside our solar system we focus on finding planets with characteristics that mimic that of Earth. Finding a habitable zone planet comparable to Earth in size is a major step forward," Elisa Quintana, research scientist at the SETI Institute at NASA's Ames Research Center in Moffett Field, Calif., said in the release. She also was lead author of the paper about Kepler-186f published today in the journal Science.
Kepler-186f is in the Kepler-186 system, about 500 lightyears from Earth in the constellation Cygnus, the NASA release said. Four companion planets, which orbit a star half the size and mass of our sun, are also in that system.
"Being in the habitable zone does not mean we know this planet is habitable. The temperature on the planet is strongly dependent on what kind of atmosphere the planet has," said Thomas Barclay, research scientist at the Bay Area Environmental Research Institute at Ames, in the NASA's release. "Kepler-186f can be thought of as an Earth-cousin rather than an Earth-twin. It has many properties that resemble Earth."
The planet’s size may be known, but determining its mass and composition will require more exploration. The NASA release said other research indicates the planet is likely to be rocky.
The Kepler Space Telescope, which simultaneously and continuously measured the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-sized planets around stars like our sun.
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