In astronomy, an analemma is a diagram showing the variation of the position of the Sun in the sky over the course of a year, as viewed at a fixed time of day and from a fixed location on the Earth. The north–south component of the analemma is due to change of the Sun’s declination caused by the tilt of the Earth’s axis, and the east–west component is due to nonuniform rate of change of the Sun’s right ascension, governed by combined effects of axial tilt and Earth’s orbital eccentricity. The diagram has the form of a slender figure eight, and can often be found on globes of the Earth.
It is possible to photograph the analemma by keeping a camera at a fixed location and orientation and taking multiple exposures throughout the year, always at the same clock time (and accounting for daylight saving time, when and where applicable). Diagrams of analemmas frequently carry marks that show the position of the Sun at various closely spaced dates throughout the year. (The image of the analemma on Mars is only a simulation) (source)
Image credit: Tunç Tezel, Dennis Mammana & Anthony Ayiomamitis
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