Carl Sagan passed away 15 years ago today. Sagan was a gifted astronomer, astrophysicist, writer, and evangelist of science; he was best known for his TV series Cosmos, and his novel Contact, which was later made into a movie. Both dealt with the big questions of science (including are we alone?), and humanity's place in the cosmos -- about finding meaning through the scientific method, and experiencing wonder in the process. Sagan was a tremendously humane man, whose warmth and generosity of spirit... READ ON