NASA finds Earth-size planets outside solar system

WASHINGTON Wed Dec 21, 2011 9:22am EST

An artist's rendering shows a planet called Kepler-20e. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass.   REUTERS/NASA/Ames/JPL-Caltech

An artist's rendering shows a planet called Kepler-20e. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass.

Credit: Reuters/NASA/Ames/JPL-Caltech

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WASHINGTON (Reuters) - NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system, a milestone in the search for planets like the earth, the space agency said on Tuesday.

The planets, called Kepler-20e and Kepler-20f, are the smallest planets outside the solar system confirmed around a star like the Sun, NASA said in a statement.

The planets are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface.

"This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them," Francois Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, said in the statement.

The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth.

Kepler-20f is slightly larger than Earth, measuring 1.03 times its radius. Both planets are in a five-planet system called Kepler-20, about 1,000 light-years away in the constellation Lyra.

Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days.

Kepler-20f, at 800 degrees Fahrenheit, is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass.

The Kepler space telescope detects planets and planet candidates by measuring dips in the brightness of more than 150,000 stars as planets cross in front their stars.

NASA is an acronym for National Aeronautics and Space Administration.

(Reporting by Ian Simpson; Editing by Jerry Norton)

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Comments (20)
rakolina wrote:
This is nothing new! Kepler’s candidates list of 1235 was announced in February, and a list of systems with planets in habitable zone has been steadily growing for the past year.

Dec 21, 2011 9:00am EST  --  Report as abuse
USAPragmatist wrote:
Let us get James Webb up there, then we can start taking spectrum of the light from these planets, THEN it is going to be interesting.

Dec 21, 2011 10:14am EST  --  Report as abuse
BruceBanner wrote:
@rakolina
This IS new – that candidate list was of ALL extrasolar planets (any size, any orbit, any star in the Kepler field of view):
http://en.wikipedia.org/wiki/Kepler_(spacecraft)#Extrasolar_planets_detected

This announcement is the first of Earth-like planets (0.87 and 1.03 times Earth’s radius) orbiting a Sun-like star. But they are NOT in the habitable zone – when they find that, it will be another first.

These planets are 1000 light years away – makes you wonder how many other civilizations in the galaxy are examining Earth, a nice small planet in the habitable zone of a nice stable star, with thoughts of colonizing. Or, who’s already been here in the last 85 million years…

Dec 21, 2011 10:23am EST  --  Report as abuse
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