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After locating more than 340 planets orbiting other stars, astronomers have found two that are the most similar to Earth so far. The most recently discovered one is less than twice the size of Earth, making it the smallest exoplanet — or extrasolar planet — found to date.
The second one was found in 2007, but new observations have shown it is the only exo planet to date that orbits its star in the so-called habitable zone, where water remains a liquid. Thus, it is the only exoplanet discovered that is likely to have oceans. Both orbit the same star, a dwarf 20 light-years from Earth called Gliese 581, European researchers said Tuesday.
