Analemma (3-year time-lapse)

Timelapse of the Sun in the West, one picture every 24 hours. Watch as the Sun traces out a figure 8 in the sky each year from 2015 to 2018. The shape of this path is known as the solar analemma.

Why does the position of the Sun change each day? The Earth spins and revolves around the Sun, but the Earth's spin is tilted compared to its orbit. Sometimes the Earth's North Pole tilts toward the Sun, and sometimes it tilts away. This makes the Sun appear to shift North and South from one day to the next and creates the north-south motion in the analemma.

It takes the Earth about 23 hours and 56 minutes to spin once, but because it is also moving in its orbit, the Earth has to spin a few minutes more for the same side to face the Sun. The Earth's orbit is elliptical, and the Earth moves faster in its orbit when it is closer to the Sun. So sometimes the Earth has to spin more to return the same side to face the Sun, and sometimes it takes less time. This creates the east-west motion in the analemma.

This video was made from a series of pictures that were each taken 24 hours apart by the HPWREN cameras at the Mount Laguna Observatory in San Diego County over a 3 year period.

See also a time-lapse movie showing when and where the Sun sets on the horizon each day of the year:    • 1000 Sunsets at Mount Laguna Observatory  

Playlist with additional time-lapse astronomy videos:    • Time-Lapse Astronomy