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Astronomers find 3 alien planets smaller than Earth

January 13, 2012 9:45am
Astronomers have discovered three alien planets that they said could be the smallest yet, with one of them just the size of Mars.
 
The planets, detected using available data from the National Aeronautics and Space Administration’s Kepler mission, are 0.78, 0.73 and 0.57 times the diameter of Earth respectively.
 
“This is the tiniest solar system found so far. It’s actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy,” Space.com quoted principal investigator John Johnson of the California Institute of Technology in Pasadena as saying.
 
Space.com said the three exoplanets orbit a red dwarf star known as KOI-961, which is just one-sixth the size of our Sun and is located 120 light-years away, in the Constellation Cygnus.
 
It added the three planets orbit very close to their star, just 0.6 to 1.5 percent the distance from Earth to the Sun. Researchers said it takes each of them less than two days to orbit KOI-961.
 
“It’s almost like you took a shrink gun and zapped a planetary system, the whole thing, including the sun,” Johnson said.
 
Too hot to be habitable
 
Space.com said that while the three exoplanets are thought to be rocky like Earth, they may be too hot to be in the habitable zone.
 
“The surface temperatures of these planets range from 720 Kelvin (836 degrees Fahrenheit) to 450 Kelvin (350 degrees),” Johnson said.
 
Transit method
 
Kepler finds planets using the transit method technique - watching for tiny dips in a star’s brightness caused when a planet crosses the star and blocks some of its light.
 
“If there were small planets like these around a star more like our Sun, there’s no chance we’d find them,” Johnson said.
 
But it was an amateur astronomer, Kevin Apps, who tipped the researchers off to the fact that KOI-961 was virtually identical to the well-studied Barnard’s Star.
 
Meanwhile, the three tiny exoplanets add to an impressive list of recent discoveries by Kepler.
 
Last month, astronomers using the instrument announced the discovery of the first two Earth-size alien planets, and one slightly larger than our home planet that resides in its star’s habitable zone.
 
Kepler has so far found about 35 alien planets, and flagged an additional 2,300 exoplanet candidates that await confirmation by follow-up studies.
 
Scientists have estimated that at least 80 percent of these potential planets will end up being the real deal. — RSJ, GMA News