- WHY IT MATTERS: Speaking from the Keck Observatory atop Hawaii's Mauna Kea, planet hunter Geoff Marcy talks about finding earth-like worlds in other solar systems.
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Illustration by Lynette Cook, courtesy California and Carnegie Planet Search A planet about 22 times the mass of Earth orbits the star Gliese 436 in an artist's rendering.
Scientists have discovered dozens of planets outside our own solar system in recent years. Most of the new planets are probably huge balls of gas, more like Jupiter than Earth. But scientists say the increasing rate at which they're finding new planets make it almost a certainty that the galaxy is also swarming with smaller, rocky, and potentially habitable worlds that have so far eluded detection.
