In search of the noon analemma

I have just finished my latest analogue photography project, which, after 12 months of work, ultimately turned out to be something of a failure.

In September 2022, I set up a pinhole camera in the window of my north-facing office at Tūhura Otago Museum. I loaded the camera with a single photosensitive glass plate. At midday in winter and 1pm in summer, if the sun was visible, I opened the camera's shutter for precisely 20 seconds.

On September 23 (the day of the spring equinox), I took the last photograph. I took the camera home to develop the resulting image in my dark room (which usually functions as the Griffin whānau laundry). This week's accompanying photograph shows that I didn't set the camera angle quite right and missed the top part of my intended target, the noon solar analemma.

The analemma is the name astronomers give to the figure of eight shapes you see if you take a picture from the same place at the same time over a year. The shape's north-south component (its height) is caused by Earth's axial tilt (which is why the sun is high at noon in summer and low in winter). The east-west component or width results from Earth's tilted axis combining with our planet's ever-changing speed as we go around our parent star in an oval orbit.

A year ago, in this column, I discussed an analemma I photographed at 4pm during 2021/22. While the shape of the analemma is the same, the angle the analemma makes to the horizon changes over a day.

There are two lines on the image. The longer of the two records the sun's path on the day of the autumn equinox in March 2023 when I left the camera shutter open all day. The shorter and lower line shows the sun's course on the winter solstice afternoon in June 2023.

Thanks to the failure of this particular project, I've adjusted the camera position and have begun another year-long sequence of images in the hope I can record the whole analemma over the next year. Wish me luck!