(Every day until Christmas, I’ll be posting a science-related image.)

Day 5

Very early on the morning of June 8, 2004, a small group of people (including myself) gathered around the Rutgers University 21-inch telescope on the roof of the physics building. Ted Williams, professor of astronomy at Rutgers, took the picture above during that session, because it was no ordinary sunrise that day. While the planet Venus is a common sight either in the early morning or in the early evening, we congregated to bear witness to a very rare event: the transit of Venus across the Sun.

A transit is an eclipse, much like a solar eclipse, in which the Moon passes in front of the Sun. However, even though Venus is significantly larger than the Moon, it’s farther away from Earth, so it blocks less of the Sun’s light. It’s also a much rarer event than a solar eclipse: Venus transit happen roughly twice every century, at an interval of 8 years. This summer (June 5, 2012) also marked a Venus transit, though unfortunately the weather in Richmond, Virginia made it hard for me to see it. Transits were once used to measure the size of the Solar System; today they are used to find planets orbiting other stars.

(For a lot more about Venus transits, please read my Double X Science post on the topic! I also mentioned it briefly in an earlier post about science communication.)