The stars are out tonight. And they do more than just twinkle. These boiling balls of hot plasma can tell us something about other celestial phenomena. They betray the hiding places of black holes, for one. But they can also fool us. Find out why one of the most intriguing discoveries in astrobiology – that of the potentially habitable exoplanet Gliese 581g – may have been just a mirage.Plus, the highest levels of ultraviolet light ever mentioned on Earth’s surface puzzles scientists: is it a fluke of nature, or something manmade?And a physicist suggests that stars could be used by advanced aliens to send hailing signals deep into space.Guests: Paul Robertson – Postdoctoral fellow, Penn State Center for Exoplanets and Habitable Worlds Mike Joner – Research professor of astronomy at Brigham Young University Nathalie Cabrol – Planetary scientist, SETI Institute Anthony Zee – Theoretical physicist at the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara First aired July 23, 2014. Learn more about your ad choices. Visit megaphone.fm/adchoices