Is there anybody out there? Astronomers and dreamers have been asking this question since the dawn of humanity — and yet, the mystery remains. Are we the only life forms in the universe, or are neighbors like us lurking just beyond the reaches of our solar system? NASA has made it a mission to discover the truth. In March 2009, the space agency launched the Kepler Mission, a NASA Discovery program designed to look for possible life-supporting planets. So far, Kepler has discovered almost 4,500 potential planets. Once confirmed by follow-up studies, these potential discoveries could continue to raise the tally of exoplanets (planets outside our solar system) over its current count. Here are 10 images depicting these wild worlds.
Pictured here is an artist's depiction of Kepler-22b, which was the first exoplanet discovered by Kepler to orbit in a star's habitable zone. This means that Kepler-22b may have liquid water on it like Earth, making it our closest possible sister planet. As NASA writes, "the planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habitable zone of a star like our sun."
This story was originally written on July 2012 but has been updated to reflect current information.