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New Planet System Found—May Have Hidden "Super Earth"
An artist's impression of two Saturn-like planets orbiting the star Kepler-9.
Image courtesy NASA
Rachel Kaufman
for National Geographic News
Published August 26, 2010
A newly discovered planetary system orbiting a sunlike star may conceal a rare super-Earth, according to data from NASA's Kepler space telescope.
Launched last March, Kepler was designed to look for extrasolar planets, aka exoplanets, via transits—the periodic dimming of light from stars due to planets passing in front them, as seen from the telescope's vantage point. (Read about Kepler's first planet discoveries.)
After analyzing seven months' worth of data from Kepler, a team led by Matt Holman of the Harvard-Smithsonian Center for Astrophysics found two transiting exoplanets orbiting the star Kepler-9, which lies about 2,300 light-years from Earth.
One of the planets, dubbed Kepler-9b, takes just over 19 days to orbit its star. The other, Kepler-9c, takes almost 39 days to complete an orbit. (Find out how exoplanets get their names.)
The researchers noticed that both planets' orbital periods speed up and slow down at regular intervals. This means the two planets are locked in gravitational "resonance"—so that each planet's gravity is affecting the other's orbit.
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