This photograph shows the beginning of a new project next to Keppel Henge that started in November 2009. We've used the Keppel Henge site to create an analemma in the sky, and now with this disk we will be creating an analemma pattern on the ground.

The large disk at the end of the pole in the photograph has a hole in the centre. Each sunny day, at midday, the Sun shines through the hole and makes a bright spot on the ground. At exactly 12:22 p.m. local standard time we place a marker on the ground in the centre of the bright spot. Gradually, day by day as the spot changes its location, an analemma pattern is traced out on the ground.

The disk is about 5 meters above the ground, and it is tilted on a 45 degree angle to match our local latitude.

This shows what the hole, or aperture bright spot looks like. We are hammering in short lengths of rebar to mark the centre of each day's bright spot. The time 12:22 p.m. was chosen since it is close to the yearly average transit time of the Sun at our location.

A major challenge we anticipate will be marking the spot during the snowy winter months. Once the pattern in complete we plan to construct a small wall that follows the marked pattern. If all goes well we should be finished in late 2010.