Alien Planets Like Earth

[Jim Colyer]

https://www.youtube.com/watch?v=mjnxNGqWrHI

This documentary shown on NOVA tells the story of the Kepler Space Telescope and its search for earthlike exoplanets. Kepler found 3500 potential planets in a small patch of sky near the constellation Cygnus. Ultimately Kepler is looking for extraterrestrial life, so it is interested in planets that are the right distances from their stars so that liquid water can exist. Not too hot, not too cold! It is assumed that alien life will obey the laws of chemistry and physics. It is also assumed that the elements carbon, nitrogen, oxygen and hydrogen will play an important role along with self-replicating DNA molecules. Planet hunter Geoff Marcy turns up. There could be trillions of planets in the Milky Way.