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When astronomists first went about finding planets outside the Milky Way, the method they used could only detect planets the size of Jupiter. A good start, although not ideal if you're curious about life outside of Earth.
"But if you're looking for life as we know it, you want to find familiar planets," StarTalk Radio host Neil deGrasse Tyson tells us. "Planets maybe the size of Earth. Planets that are the right distance from their host star."
So, in order to satiate our curiousity for potential life outside Earth, NASA launched Kepler - a space observatory with the primary purpose of identifying Earth-like planets.
With well over 2,000 "planet candidates," Kepler is our "best bet for finding life as we know it," says Tyson.
Watch our video interview with Neil deGrasse Tyson to find out more about Earth-like planets and to hear his thoughts on life outside of Earth.
Produced by Kamelia Angelova, William Wei, & Alana Kakoyiannis
StarTalk Radio is a podcast and radio program hosted by astrophysicist Neil deGrasse Tyson, where comic co-hosts, guest celebrities and scientists discuss astronomy, physics, and everything else about life in the universe. Follow StarTalk Radio on Twitter, and watch StarTalk Radio "Behind the Scenes" on YouTube.