Earth-Size Planet Found that Might Hold Liquid Water

http://spaceref.com/extrasolar-planets/earth-size-planet-found-that-might-hold-liquid-water.html
4/17/2014

In a dim and faraway solar system, astronomers have for the first time discovered a rocky, Earth-sized planet that might hold liquid water -- a necessary ingredient for life as we know it.

The planet Kepler-186f is the fifth and outermost world orbiting the red dwarf Kepler-186. The slow-burning sun is smaller and cooler than our own. Too faint to be seen without a telescope, it's roughly 500 light-years away in the direction of the northern constellation Cygnus.

Two attributes make the newfound planet special. First, it's within its star's habitable zone. That's the range of orbital distances where a planet with an atmosphere could harbor lakes, rivers or oceans that wouldn't freeze or boil away. Second, the planet is about the size of the Earth.

"One of the most interesting questions in science is whether life can arise on other planets or, alternatively, if life on this planet is unique. The discovery of planets with Earth-like properties is one important link in the chain required to answer this question.

Over the past two decades, astronomers have found some 1,800 exoplanets in other solar systems. Only 20 orbit their stars in a habitable zone. But these are all thought to be much larger than the Earth, according to a news release from the SETI Institute.