Solar eclipses, such as the annular event that we had a few weeks ago, are rare events, occurring somewhere on Earth between two and five times per year. If you’re on the lookout for a total solar eclipse, you’ll have to wait about 18 months between each one. But far less common than solar eclipses is the Transit of Venus.
Today’s transit–an unusual event in which Venus will cross the path between the Earth and the sun–will begin tonight at sundown in the Western Hemisphere. If you miss it, you’ll have to wait until 2117 to catch the next series. British explorer James Cook observed a Transit of Venus almost 250 years ago as he was sailing around Tahiti on June 3, 1769, and brought back important clues that helped astronomers expand their knowledge about the size of our solar system.
Watch the video below for a description on this latest transit from the California Academy of Sciences. And check out the SLOOH SpaceCamera for a live, eight hour event that will catch the transit from a number of feeds around the world.