Only a few years ago, astronomers were thrilled if they found a star beyond the solar system harboring a single planet. Now they’re discovering more and more multiple-planet systems that may offer new clues about the formation of planets and their evolution.
In one new study, scientists have discovered a star with at least five and as many as seven planets, which would make it the richest known planetary retinue beyond the solar system. A second study has revealed a star with two Saturn-mass planets locked in a special gravitational embrace that allows astronomers to study the pair in unusual detail. Researchers also find hints of a third planet orbiting with the two. If confirmed, the planet would be the tiniest extrasolar orb known, with a diameter only 1.5 times that of Earth.
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