Astronomers on verge of finding Earth's twin

It's just a matter of time before Earth's twin can be found, scientists say. And they believe it is surely hiding somewhere in our star-studded galaxy.

Momentum is building: Just last week, astronomers announced they had discovered three super-Earths -- worlds more massive than ours but small enough to most likely be rocky -- orbiting a single star. And dozens of other worlds suspected of having masses in that same range were found around other stars.

"Being able to find three Earth-mass planets around a single star really makes the point that not only may many stars have one Earth, but they may very well have a couple of Earths," said Alan Boss, a planet formation theorist at the Carnegie Institution of Washington in Washington, D.C.