【科学60秒】寻找“地球号” (双语有声)

Search Unearths Plethora of Earth-Mass Planets

If there's a line in Vegas on the odds of life on another planet, now might be a good time to place a wager. A study in the journal Science examined 166 sun-sized stars and found nearly one in four had rocky, earth-sized planets in close, Earth-like orbits. The finding might chart a new course for extrasolar planet research.

Most planet-formation models predict a “planet desert” within one astronomical unit (or the average distance from the Earth to the sun) of a host star. Gaseous planets like Jupiter or Saturn, which form much farther away, on the cold side of what’s called the “ice line,” are thought to be more common.

But a team of researchers at Hawaii's Keck observatory cast their eyes on stars similar to our sun. Twenty-three percent of those stars had small, rocky planets orbiting right in the range where the predicted “planet desert” should be. [Andrew Howard et al., "The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters"]

The researchers say their discovery calls for substantial revisions to current astronomical models. It also makes the possibility of life on some similar planet spinning a similar, habitable distance from its sun seem like a better bet.