A total lunar eclipse occurs when the Earth passes between the Sun and the Moon, blocking the Sun’s rays from reaching the Moon. In fact, some rays do reach the Moon, accounting for the ruddy orange glow. It starts at 2:20 p.m. ET and Google is broadcasting it live (June 15, 2011) from 2pm to 6pm. It should last for about 100 minutes. You can view this eclipse on the ground if you’re in South America, Europe, Africa, Asia or Australia.
And, of course, the Google Doodle of the day is an interactive lunar eclipse: