Monday, June 11

The transit of Venus seen from Rarotonga

Stargazers around the world focused on our local star, the sun, last Tuesday (5 June) to witness a rare celestial event. The planet Venus was silhouetted as it passed in front of the sun – the transit of Venus – and this won’t happen again for another 105 years, until December 2117.
The transit was due to begin just after midday (local time) and to end at about 6.43pm (although that wouldn’t have been visible here because sunset on Rarotonga was at five past six). But in the morning it looked as though nobody would see anything as thick clouds covered the island. There were even a couple of brief showers.
We got the camera set up anyway. It’s not particularly fancy; a point-and-shoot superzoom (Nikon Coolpix 500). We already had a solar filter left over from the 2010 total eclipse.
When cameras like this are zoomed to the max, the lens barrel extends out an extra 5cm from the body so we chopped up a plastic water bottle, painted it black and attached it to the camera and the filter using duct tape. The diameter was perfect and I guess it’s a different way to reduce waste!
As noon approached the weather began to brighten up and by the time the transit started the sky was clear, at least in the area around the sun.
Our set-up wasn’t sophisticated. The camera was on a tripod and every now and again we took a picture setting the focus manually on infinity, and exposing at 1/500 sec at f8. As the sun tracked across the sky we panned the camera to follow it. We drained several batteries and had to remove the camera to replace them and at five o’clock, when the sun was about to disappear behind some trees we upped sticks and headed to Nikao beach to finish off. That’s why the video is somewhat jerky! But, hey, it was totally awesome being able to see it.
The video is made up from about 120 still frames speeded up to last ten seconds as opposed to the actual five and a half hours the transit took.
What made things even better was the amount of interest it generated locally.
My husband Phil wrote an article for Cook Islands News before the event (Transit of Venus) and teachers in Rarotonga and Mangaia took the opportunity to introduce students to the thrill of astronomy.
In Mangaia the kids were able to watch using eclipse glasses left over from 2010 (the solar eclipse was total on that island) and at Tereora and Nukutere colleges on Rarotonga the heads of science Des Duthie and Russell Grieve used their own telescopes to set up projected images so students could view the historic occasion. (See Cook Islands News coverage here.)