How we found hundreds of potential Earth-like planets

(NOTE: This talk was given in 2010, and this field of science has developed quickly since then. Read "Criticisms & updates" below for more details.) Astronomer Dimitar Sasselov and his colleagues search for Earth-like planets that may, someday, help us answer centuries-old questions about the origin and existence of biological life elsewhere (and on Earth). Preliminary results show that they have found 706 "candidates" -- some of which further research may prove to be planets with Earth-like geochemical characteristics.