What are the odds that life exists elsewhere in the universe, and what are we doing to find out? Topics in this video range from the meaning of the Drake Equation and assumptions being used to narrow the vast field of stars in which scientists are searching, to the Doppler and transit methods of discovering extrasolar planets, to three initiatives that will help pinpoint probable life-supporting worlds: the Kepler mission, the spectroscopic Life Finder mission, and the Terrestrial Planet Finder observatories.

Encoded with permission for digital streaming by Infobase on June 21, 2006. Learn360 is distributed by Infobase for Films for the Humanities & Sciences, Cambridge Educational, Meridian Education, and Shopware.

Have They Already Been Here? (3:21) -- The Search for Extraterrestrial Intelligence (6:05) -- The Odds (8:12) -- Extrasolar Planets (6:18).