The discovery of a planet that orbits two stars-an arrangement that some scientists previously thought existed only in science fiction-was announced by astronomers at NASA‘s Ames Research Center in Mountain View, California. Kepler space telescope detected the planet, which scientists named Kepler-16b. The research team uses data from the telescope, which measures dips in the brightness of more than 150,000 stars, to search for transiting planets. (A transiting planet is a celestial body that moves across the face of another celestial body, hiding a small part of it.) Kepler-16b is about 200 light years from Earth and about the size of Saturn. Astronomers believe that Kepler-16b is gaseous and too cold to harbor life. It orbits the two stars in 229 days. The stars in turn circle each other.

“This discovery confirms a new class of planetary systems that could harbor life,” notes Kepler astronomer William Borucki. “Given that most stars in our galaxy are part of a binary (two star) system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now.”

Additional World Book articles:

• Astronomy
• Kepler, Johannes
• Hubble Space Telescope