2003-05-07: Transit of Mercury

Here are scans of three sketches I made during the transit of Mercury during May 2003.

For this event I assembled (calling it "constructed" would be rather overstating the case) a contraption consisting of a cardboard box mounted on a rather wobbly tripod with a pair of Helios 15x70s projecting through round holes cut in the front. This allowed pretty good eyepiece projection.

Mercury appeared as a small round disk. It was quite apparantly darker and sharper edged than the sunspots which were also visible. In the sketches, it is the dot progressing across the bottom of the sun images, from roughly the eight o'clock position to six o'clock.

These sketches are shown as they were projected and are therefore flipped with respect to the view one would get looking directly at the sun (with suitable protection, presumably).

Observations were made from Wycombe Air Park (EGTB) near High Wycombe, UK. The observation position was N51°36.34' W000°48.41'. The site was chosen for its good horizon to the east so we could see the early parts of the event. I was there with Chris Rowland who had his 11" Celestron with a webcam hanging off the back and a solar filter on the front. We ran the web-cam into my laptop and got about 2 CDs full of images.

Unfortunately, we missed the first few minutes of the transit as we were a bit slow getting set up but we were very luckly to watch the rest under clear skies. Also, I made my first sketch on a scrap of paper rather than in my notebook so that priceless observation is now gone for good. I also took lots of pictures of the projected image, the projecting contraption and the general scene with my 35mm film camera then discovered it had no film in it. A minor advantage of digital cameras is shown here, perhaps - but also, of the advantage of planning ahead and making sure your toys are set up properly.

Two transit sketches

Third transit sketch

General view of our observation site

Chris distracted me with coffee then took this picture showing his Celestron with the solar filter fitted (a 90mm off-axis disc sandwiched between sheets of white plastic) and my eyepiece projector.

View of projected image

A view of the projected image of the sun. It is, unfortunately, over exposed so it is not possible to see Mercury or the sunspots. The elliptical shape is a result of the camera not being orthogonal to the projection plane.

Solar projection contraption

A slightly more anatomically useful view of the eyepiece projection contraption.

Photos courtesy Chris Rowland.