analemma


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analemma

(an-ă-lem -ă) The shape resembling a figure of eight obtained by plotting the position of the Sun relative to the intersection of a meridian and the celestial equator at a fixed (mean) time every day throughout the year. The analemma's vertical extent is a reflection of the changes in the Sun's declination arising from the inclination of the Earth's axis to the perpendicular to its orbit. The horizontal extent arises from the fact that the Earth's orbit is elliptical, which produces a difference between the length of the apparent solar day (the actual time between successive meridian transits of the Sun) and the mean solar day.

analemma

[‚an·ə′lem·ə]
(astronomy)
A figure-eight-shaped diagram on a globe showing the declination of the sun throughout the year and also the equation of time.
(civil engineering)
Any raised construction which serves as a support or rest.

analemma

1. A retaining wall at the side of an ancient Greek or Roman theater.
2. Any raised construction which serves as a support or rest.
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References in periodicals archive ?
An analemma is the figure-eight pattern that the Sun makes in the sky when photographed at the same time periodically throughout an entire year.
If the project goes through, the Analemma Tower will be the first ever revolving building outside Earth, as it would travel between hemispheres on a regular daily schedule.
Details of the project, the photograph's subtleties, and the analemma in general are in the June 1979 issue of Sky & Telescope magazine, which can be purchased for immediate digital download at www.
The Sun is not on the meridian at noon at the solstices, so the analemma is skewed and does not line up with the vertical axis.
The analemma offers a graphic display of one of the lessons a horologium can teach: the difference between clock time and sun time.
If you're planning to capture a "tutulemma" (an analemma that includes August's eclipsed Sun), these plots show its correct orientation in the sky from two sites along the path of totality.
If our Earth had a perfectly circular orbit and no axial tilt, the Sun would always appear at the same point in the sky at the same time of day throughout the year and the analemma would be a dot.
This led me to set my sights on the ultimate long-term skyscape photograph: recording the analemma.
By doing so he recorded the analemma in the sky--it's the flattened figure-8 seen on globes.
Apparently no one has ever recorded the analemma from a polar region.
The analemma is the Sun's position on the sky as seen at the same time of day through the year).
I am a quarter of the way through a year-long analemma photograph, for which I'm acquiring an image every few days with a digital camera on a fixed bracket outdoors.