Why the Transit of Venus is So Rare

The transit happens when Venus crosses the disc of the Sun as seen from Earth. In 1639, the first ever recorded scientific observation of the Transit of Venus occurred as observed by Horrocks and Crabtree.

It occurs twice in eight years, in June or December, and then not again for over 100 years. So if you miss it in June 2012, then you won’t be able to see this rare event again until December 11, 2117. In other words, this is a once in a life time event as far as seeing it as a pair. The last occurance was eight years ago on June 8, 2004.

The venus transit’s rareness can be blamed on Math; geometry to be specific. Venus and Earth are not often lined up in the exact same orbital plane as it relates to the Sun. They occur in patterns with pairs of transits eight years apart separated by long gaps of up to 121.5 years.

by FLH