Take one Sun-like star, two scant Saturns, one maybe-Earth, and combine over high heat, and you've got Kepler-9, the latest addition to our growing catalog of planetary systems and the first sample of 400 elite planet-candidates that the Kepler Space Telescope team has been keeping under wraps.
Scientists analyzing data from Kepler, NASA's flagship planet-hunter, announced earlier this week that they have confirmed two Saturn-sized planets in tight orbits around Kepler-9, one of more than 100,000 stars in Kepler's field of view. These gas giants create mini-eclipses each time they pass in front of their parent star--that's how Kepler spotted them. Now, follow-up observations from the Keck telescope in Hawaii have verified that these periodic blips really are planets. Just a bit smaller and less massive than Saturn, the planets orbit closer to their star than Mercury does to the Sun. Because their orbits bring them so close to each other, they exert a measurable gravitational tug on each other: The inner Saturn is speeding up and the outer one slowing down by a few minutes every go-round.
But what about that maybe-Earth I promised? Until its mass is confirmed by follow-up observations, it's just an "Object of Interest," but here's what we do know: It orbits every 1.6 days or so and is about 50% larger than Earth. It's not the smallest exoplanet discovered so far--earlier this month, a European team announced that a planet candidate with as little as 1.4 Earth masses could be the record-breaking seventh member of a planetary system only 127 light-years away--and it would be scorchingly hot. So while it might be "Earth-sized," it is definitely not "Earth-like." We'll have to wait a while for truly Earth-like planets to start appearing in Kepler data.
For more on the hunt for Earth-like planets, check out NOVA scienceNOW's Hunt for Alien Earths.