Analemma

Despite what your dirty mind is thinking, an analemma is a term used in astronomy to describe the figure traced in the sky when the position of the Sun is plotted at the exact same time each day over a period of a year, from a fixed location on Earth.

Due to the tilt of Earth's axis and its elliptical orbit around the Sun, the location of the Sun is not constant from day to day when observed at the same time each day. This results in the analemma curve looking like a figure 8. The plot will also have a varying incline depending on where one's geographical latitude is.

If Earth's axis had no tilt and a perfectly circular orbit around the Sun, then the Sun would always appear at the same point in the sky at the same time throughout the day, all year long, resulting in the analemma being just a single dot.

The figure 8 pattern the Sun makes can be a rather difficult phenomenon to capture in a photograph, since it requires taking a multiple-exposure picture of the Sun at the exact same time, in the exact same position, once or twice a week for an entire year. That's quite a commitment of time and quite a feat of precision to not screw up.

Obviously, taking a multiple-exposure photograph is much easier to do now with digital cameras, but it can still be fairly difficult. So difficult in fact that only about 20 people worldwide have ever released a successful picture of an analemma.

The very first one created was on a single frame of physical film in 1978 by Dennis di Ciccio. Using a solar filter with the exposures, it is also one of the few that doesn't have a composited foreground. 

Today, most photograph the analemma first, then digitally composite a foreground in at the end, since it can be too difficult to accommodate for two different exposures (one for the sky and one for the foreground) over the length of an entire year. By digitally inserting the foreground at the end, it successfully eliminates a variable, and one less variable to plan and adjust for only increases one's chances at creating a successful analemma photograph.

Below is one such photograph, taken in 2006 in Turkey. It not only traces the Sun's path over an entire year, but also includes a total solar eclipse.

 

I used to be quite the astronomy nut when I was younger (still am to some extent) and I've always held an active interest in photography for many years. It's understandable then, why something like this which combines both interests, would intrigue me so and warrant a discussion such as this post.