The earth's orbit around the Sun is not a perfect circle. It is an ellipse, albeit not a very flattened one, and this leads to a number of interesting observational effects. One of these is the analemma, the apparent path traced by the Sun in the sky when observed at the same time of day over the course of a year. The path resembles a lopsided figure eight (which is printed on some globes).

When measuring the Sun's position in the sky every day precisely at noon, over the course of a year the Sun appears to move higher in the sky as summer approaches and then move lower as winter approaches. This occurs because the tilt of Earth's axis causes the Sun's apparent celestial latitude, or declination, to change over the course of the year.

However, at some times of the year, the Sun will appear slightly...