Transits of Venus—when Venus moves visibly across the sun—are among the rarest of predictable celestial phenomena. How rare?

Well, this phenomenon, which occurs in pairs spaced eight years apart, has only happened four times in modern history and today was one of those days!!!

The last correlating pair of transits occurred in:

1631 and 1639

1761 and 1769 (Captain Cook saw this one from Tahiti)

1874 and 1882 (King David Kalakaua set up veiwing stations for this one.)

2004 and 2012 (TODAY!! We saw this one!!!)

How important?

The first correlating pair noted in modern history in 1631 and 1639 helped physicists and mathematicians determine how big the universe was. They got it wrong, of course, but they were like a zillion times closer after this than they were when they thought the sun rotated around the earth.

Today we watched this event unfold on the beach in Waikiki with the Institute for Astronomy (University of Hawaii).

With our naked eyes. On huge telescopes. On a televised screen on the beach of video taken from the top of Mauna Kea on the Big Island.

It was AWESOME!!!

Almost Magical.

Rare: Handout image courtesy of NASA shows the planet Venus at the start of its transit of the Sun, June 5, 2012. This won't happen again until 2117