Yesterday evening Laura and I headed to to Furman to observe the transit of Venus, as the planet made its way across the surface of the sun. This astronomical event happens every 120 years, and occurs in pairs, separated by 8 years. The last transit was in 2004, and the next one won’t be until 2117.
It didn’t look like the weather was going to cooperate. Heavy clouds obscured the sun, but there were enough breaks to make at least a momentary observation a possibility. So, we made our way down to the central quad area of the Townes Science Center at Furman, where Dr. David Moffat had two telescopes set up, and where others were gathering.
David had set up up two large telescopes. One was aimed at a piece of white poster board so that more people could see the passage. Another had a sun filter for direct observation, as well as another spotting scope attached so that two people could be making direct observations at the same time.
Other observing methods were on display, as well. One observer had made his own camera obscura using a box and a sheet draped over the back as a blind. I’m not sure how well that worked out for him. Laura had brought a couple of index cards with holes punched in two of them – the method we normally use for observing eclipses. Unfortunately, it doesn’t produce enough detail to see the transit. At one point I snagged a pair of binoculars from my car to try the same trick David was using with the telescope. That worked marginally better than the pinhole, but was still not up to the task.
The biggest problem, though, were the clouds. We left the gathering to head up to Laura’s office to watch the live webstream from the observatory at Mauna Kea. About the time we got up to the chemistry department, the sun slipped out, so we headed back down. And just as soon as we got down, the sun went away again, tantalizing us. Many in the crowd tried pulling up the video stream on smartphones and computers out in the courtyard.
Eventually the sun broke through for one more view. I got to see it through both eyepieces of the direct observation telescope, and we had a good projected image from the other telescope.
…and then the sun went away again.
Paul W. thought that if we sang “I’m Your Venus” by Shocking Blue it would help. At least we tried pulling up a YouTube video of the song. It didn’t help. One of the young coeds asked why we were playing the music for a razor blade commercial, not knowing that it was actually a song from the 1970’s.
So, with the clouds not cooperating, Paul, Laura and I abandoned the observation post and headed for dinner. Over dinner we discussed the scientific significance of the transit. In the 1700’s the observation sparked one of the first global scientific studies ever attempted. Edmund Halley had proposed that remote observations of the transit would help establish better measurements of distances within the solar system. In 1761, during the first of the pair of transits, war and other problems prevented the expeditions from getting underway. However, in 1769 Captain James Cook on the HMS Endeavor was able to make an observation from Tahiti as part of his famous first voyage.
An article from Nasa Science puts Cook’s voyage into perspective…
On August 12, 1768, His Majesty’s Bark Endeavour slipped out of harbor, Lt. James Cook in command, bound for Tahiti. The island had been “discovered” by Europeans only a year before in the South Pacific, a part of Earth so poorly explored mapmakers couldn’t agree if there was a giant continent there or not. Cook might as well have been going to the Moon or Mars. He would have to steer across thousands of miles of open ocean, with nothing like GPS or even a good wristwatch to keep time for navigation, to find a speck of land only 20 miles across. On the way, dangerous storms could (and did) materialize without warning. Unknown life forms waited in the ocean waters. Cook fully expected half the crew to perish.
It was worth the risk, he figured, to observe a transit of Venus.
Based on these observations it was determined that the distance from Earth to the Sun was from 93,000,000 to about 96,000,000 miles, the first fairly accurate estimates for that distance.
As for our observations, the sun never really came back out, so we had to content ourselves with online views and the memory of our brief glimpses.
However, some of my friends were luckier. Two of my Flickr friends, Tim Linder (Enterprise NCC-1701) and Carolyn Smith (Seneca Photo) were able to get good shots. Here’s Carolyn’s shot through a Meade telescope…
…and here’s Tim’s photo, taken through a Celestron telescope.