Thursday, June 7, 2012

Transit of Venus

Venus Transit Observatory, Boulder Creek, CA
I had heard that there was to be a transit of Venus on June 5 (which also happens to be my son's birthday) so I constructed a solar observatory on my deck in Boulder Creek to observe this event. The instrument consisted of a pair of 7 x 50 binoculars duct-taped to a tripod which focused the sun's image on a piece of white cardboard which was fixed at the proper distance and angle with a plastic milk crate and some books. At approximately 3 PM the silhouette of Venus began to appear on the lower right edge of the Sun's image and to move slowly from right to left across the Sun's disc.

Venus transit in progress
The transit itself looks like nothing so much as a speck of dirt until you realize that the object that's making that speck is an Earth-sized planet about 30 million miles away traveling across the face of the Sun which is about 100 million miles away.

Transits of Venus are rare--only eight have occurred since the invention of the telescope. These transits occur in pairs spaced 8 years apart--today's transit was the second member of the pairing. The first of the pair occurred on June 8, 2004. These pairs are separated by periods of approximately 100 years so an observation of a transit of Venus is a once-in-a-lifetime event. (Actually twice-in-a-lifetime). The next transit is due to occur in the year 2117.

My deck is not ideal for solar observations. Around 4:30 PM the Sun dipped below the redwoods so I was able to catch only about an hour and a half of this century's final transit of Venus.

Venus transit just before Sun hits trees.

1 comment:

Anonymous said...

Well done, Nick! Wish I'd thought of that trick. You're the physicist!