Galileo's Pendulum

Today—November 9, 2012—would have been Carl Sagan’s 78th birthday. Sagan of course was a prominent planetary scientist, co-founder of the Planetary Society space exploration advocacy group, and (most famously among non-scientists) a writer and television host. He co-wrote and starred in the iconic PBS series Cosmos, and wrote the novel Contact (the basis for the 1997…