The upper left corner shows the sky on July 28, 2009, and then each successive day is in the next rectangle over. As the video progresses, you see the same time of day in each video; there’s a clock in the lower right that displays the time. Each video starts at about 4:00 a.m. and ends at 8:30 p.m.

Suddenly, the longer cycles become obvious: In the summer, the days are longer, and the Sun rises earlier and sets earlier. So the boxes showing the summer sky—at the top and bottom of the main video—get bright first and dark last. Winter days are in the middle of the main video (New Year’s Day is roughly in the middle), with the Sun rising later and setting earlier.