Planet hunters find an Earth-mass planet and a potential water world

That's what's happening as planet-hunters digest the news that European astronomers have detected planet No. 4 orbiting a star with the imaginative moniker: Gliese 581. The new planet has 1.9 times Earth's mass, making it the tiniest exoplanet astronomers have bagged to date.The golden Easter egg in this hunt, of course, is the elusive Earthlike planet orbiting a star in its habitable zone. There, it's not too hot and not too cold, but just right for liquid water to gather and persist on the planet's surface.To spot a planet this small, and use an Earth-based telescope to do it, is a big deal

To read more click here: Planet hunters find an Earth-mass planet and a potential water world