Kevan Karanjia, Staff Writer
December 28, 2012 — Is there another Earth-like planet in the universe? That's the question that has been pondered for generations and according to some scientists, might be answered in 2013.
Astronomers have come close to finding planets with suitable conditions for life but nothing has completely matched the conditions of Earth.
More than 800 "exoplanets" — objects orbiting a sun-like star that share one or two key traits with our own world — have been discovered since 1995 but none can be considered "another Earth."
Many of the newly-found planets were either too big or orbited too close to their star for life to be remotely possible.
Now with the help of NASA's Kepler Space Telescope, astronomers believe they will soon find a twin Earth.
NASA has already confirmed the existence of Kepler-22b, the smallest planet found to orbit a star similar to our sun.
Scientists don't yet know what Kepler-22b is predominantly composed of but its discovery is a step closer to finding Earth-like planets.
"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA`s Washington headquarters, in a press release. "Kepler's results continue to demonstrate the importance of NASA's science missions, which aim to answer some of the biggest questions about our place in the universe."
The Kepler Telescope has already flagged more than 2,300 potential planets since its launch in 2009.
Around 100 of those have been confirmed as exoplanets, but mission scientists estimate that at least 80 percent will end up being better.
Scientists have been looking for objects in a star's "habitable zone," the area where planets orbit at the right distance to maintain liquid water on its surface.
Kepler spots planets by highlighting variations in brightness from its perspective, caused when they move in front of their star.
The telescope needs to witness three "brightness dips" to detect a planet.