Thursday, June 7, 2012

Not-so-Rapid Transit

On Tuesday, June 5, we were on a bike ride around Corvallis when I realized that the sun was out, so we went back to Becky's house to watch something we won't see again - the transit of Venus across the face of the sun. Using the solar-filtered binoculars gave the clearest view, but with the telescope (with solar filter of course - don't want any burned retinas or cameras) we got to take some pictures. Lots of people came over for a look too, mostly at Ciel's invitation. She wanted to turn this into a community event!

Venus looked like a little dot in front of the sun, so Ciel said "Venus is really small"! When I told her it's almost as big as the earth, she said "the sun is really big"! I worked out later that because Venus is closer to us than the sun, it looks bigger than it would if it were the same distance as the sun - by about a factor of 3! Venus is about 108 million km from the sun, and we're about 150 million km from the sun, so Venus would be less than 50 million km from us during the transit. That little dot would be a lot littler if Venus were right on the surface of the sun! Of course, it wouldn't last long there, at 5700K...


edit: The picture above was taken with a webcam adapted to the eyepiece of my little 70mm refractor - the other dark blob near the bottom of the sun's image is probably just a speck of dust on the sensor or something. I certainly didn't get a shot as good as this!

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