Earlier this month, I took some images of Pluto on two nights, separated by three days. Sky and Telescope's July 2010 issue pointed out that in early July, Pluto would pass in front of a dark cloud of gas and dust in the Milky Way, making the little dot of light a bit easier to find, so I gave it a shot with my 12-inch telescope and CCD camera. Success!
One can barely see the motion of Pluto during each individual night, using a sequence of images taken over 2 or 3 hours, but it's really easy to find the object when one compares pictures taken on the first night with pictures taken on the second night.
I was inspired by the apparent motion of Pluto against the distant stars to see if I could work out the distance between the Earth and Pluto, using my pictures and bit of trigonometry. With a bunch of simplifying assumptions, the answer is "yes, and it's not that difficult, either." So, I wrote a detailed description of the procedure and made up a little worksheet, thinking that perhaps some of my students might like to give it a try.
Before they see it, however, I'd like very much to receive comments and feedback and corrections from other people. So, I'm asking BAUT readers to look at the pictures, read the words, and, if they dare, give the calculations a try. You can find a web page with instructions at
and the worksheet at
Please tell me what you think!