Analemma

An analemma is a photograph or diagram showing the position of the Sun in the sky, as seen from a fixed location on Earth at the same mean solar time, as that position varies over the course of a year. The diagram will resemble the figure 8.

The north-south component of the analemma results from the change in the Sun’s declination due to the tilt of Earth’s axis of rotation. The east-west component results from the non-uniform rate of change of the Sun’s right ascension, governed by the combined effects of Earth’s axial tilt and orbital eccentricity.

To take a photograph of an analemma, one must keep a camera at a fixed location and pointing to the fixed orientation throughout the year, then taking multiple exposures every few days, at the same time of day, disregarding daylight saving time.

The analemma is consistent with the fact that the Earth is a rotating sphere, with a tilted axis rotation, and is in motion around the Sun, with a somewhat eccentric orbit.

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