An analemma is a composite photograph of the sun's position, taken from the same place at the same time of day (ignoring Daylight Savings) at regular intervals. The photo below traces the sun's path in the sky over 2010, with each image of the sun separated by about 10 days:
In the Summer, the sun rises high in the sky; in the Winter it barely makes it over the horizon (and, if you live above the Arctic Circle or in Antarctica, it never rises at all). The elegant figure-eight shape is caused by the tilted angle of the Earth's axis as it revolves around the Sun -- think of it like a warped bicycle wheel floating in space, viewed from edge on.
This image comes from the National Geographic gallery linked below; follow the link for other pictures of analemmas, especially the first analemma ever made, from 1979.
Happy New Year, everyone!
National Geographic: Sun Pictures: A Full Year in a Single Frame
Just a slight clarification...the "8" shape is a combination of the tilt of the earth's axis (causing the up and down motion of the sun in the analema) and the elliptical shape of the earth's orbit (causing the left/right motion).
Posted by: Kevin Wright | December 31, 2010 at 10:34