Jan 29th, 2017: Solar Analemma

[xoxoxoBruce]

The Solar Analemma sounds like an energy efficient enema, but it's not.

Analemma photographs are made by taking a picture of the sun from the same place at the same time of day once or twice a week, generating 30 to 50 frames.

Easier said than done, photographing the Sun requires careful prep and the right equipment, plus it takes a full year, making it the most difficult phenomenon to capture. Only 20 people have done it successfully.

The sun makes this shape over a year because Earth rotates on a slightly different axis than the sun, and our planet also travels on an elliptical orbit. As one hemisphere of Earth tilts farther from the sun, the arc of the sun's daily path seen from that location lowers toward the horizon. The sun's arc then gets higher in the sky as the tilt reverses. The sun's highest point in the sky, seen in this analemma, occurs during the summer solstice, while its lowest point is during winter solstice.

This description is from National Geographic, but the picture is not from their site.