NASA's Kepler space telescope has found two planets that are perfectly sized and positioned to potentially hold life.
NASA scientists are not saying that they actually have discovered life on the newfound planets, which are about 1,200 light years away. However, do say they're one step closer to finding a world similar to Earth that orbits a star like our sun.
"The Kepler spacecraft has certainly turned out to be a rock star of science," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate. "The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity."
Kepler, NASA's planet-hunting telescope, has found other planets in other star systems in the past, but they didn't meet all the criteria that would enable them to support life as we know it. The planets, for example, need to be in what scientists call the habitable zone, which is a range of distance from its star so it is neither too hot nor too cold to hold liquid water.
And previously discovered planets often were simply too big and more likely to be gas balls than rocky planets like Earth.
NASA noted today, however, that the two newly found planets -- Kepler-62-e and Kepler-62f - are quite similar to our own Earth.
Compared with Earth, Kepler-62f is 40% larger than Earth, making it the exoplanet closest to the size of our planet known in the habitable zone of another star, according to the space agency. It's also thought to be a rocky planet.
And Kepler-62e orbits on the inner edge of the habitable zone and is about 60% larger than our own planet, NASA noted.
The two exoplanets have three other planets in their system but they orbit much closer to their star, so are too hot and inhospitable for life as we know it.
"We only know of one star that hosts a planet with life, the sun," said Thomas Barclay, a Kepler scientist, in a written statement. "Finding a planet in the habitable zone around a star like our sun is a significant milestone toward finding truly Earth-like planets."
The Kepler space telescope, launched into space in the spring of 2009, continuously measures the brightness of more than 150,000 stars, enabling scientists to detect any dimming in their brightness caused by orbiting planets passing in front of them.
Kepler is NASA's first mission capable of detecting Earth-size planets around stars like our sun.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is firstname.lastname@example.org.