Paul Doherty, Senior Scientist at the Exploratorium in San Francisco (Patio Plasma in Second Life).
An overview of how eclipses and transits happen. (A transit of Venus
is happening on June 5/6, 2012.) How to look at them safely. How
transits were used to measure the solar system. How the Kepler satellite
is searching for exoplanets (planets outside our solar system) by
looking for transits.