During the lockdown, the only place considered as “outside” is my balcony. While spending most of my time “Outside”, I have been more aware of the sky and realized that the sun doesn’t set at the same spot. Not only that, but it also doesn’t set at the same time. Is there a pattern that we can understand a bit better?
The first observation has to do with the sun’s position. The sun does not always set due west. In the summer, it sets to the north and in winter, it sets to the south. The northern-most and southern-most points that the sun reaches while setting are at the summer and winter solstices. The second observation has to do with the time of sunset.
We know that days are longer in the summer and shorter in the winter; this means that the sun sets later in the summer and earlier in the winter. If we combine these two observations, what do we expect? Tracking the position of the sun at the same time every day of the year would result in an approximately slanting line. This pattern is actually a ‘figure of 8’ that is slanted from lower-south to upper-north. This pattern is called an analemma and it repeats every year.
There are so many things around us that we are not even aware of. There are cycles everywhere in nature. In biology, chemistry, physics, math, and even astronomy. The weather also follows roughly an annual cycle and the sun follows a daily cycle. These are examples of cycles that are very obvious to us. An analemma is a cycle that is not obvious until there is a pandemic and we get to wondering how the sun is moving.
For more information see Wikipedia, The Astronomy Corner, Stanford.