NASA’s Kepler space telescope has located a solar system that contains the smallest exoplanet found to date. Labeled Kepler-37b, it’s about the size of Earth’s moon, and orbits its parent star, Kepler-37, once every 13 days. As the innermost of the three planets in the system, it’s estimated to have a rocky surface, a temperature of about 800 degrees Fahrenheit, and no atmosphere or water. The other two planets, 37c and 37d, orbit the star every 21 and 40 days respectively.
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What’s the Big Idea?
Until now, many of the exoplanets discovered by Kepler have been Earth-sized or larger. NASA’s Thomas Barclay says the Kepler-37 system represents “a great diversity in planetary systems…This is the first time we’ve been able to probe the smallest range, smaller than anything we have in our solar system.” Kepler-37 is a yellow star that’s slightly smaller and cooler than our Sun, and resides about 210 light-years away. Astronomer Eric Ford says in a paper published in Nature that the discovery of this system “lends weight to the belief that planet occurrence increases exponentially with decreasing planet size.”