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Analemma

Posted by AT
Wikipedia definition : an analemma (/ˌænəˈlɛmə/; from Ancient Greek ἀνάλημμα (analēmma) 'support') is a 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 a figure eight. Globes of Earth often display an analemma as a two-dimensional figure of equation of time vs. declination of the…
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The Tolsey Clock

Equation of Time

Posted by AT
Equation of time is the difference between apparent solar time and mean solar time. EOT = apparent solar time – mean solar time Wikipedia defines EOT by the follwoing: The equation of time describes the discrepancy between two kinds of solar time. The word equation is used in the medieval…
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Magnificent CME Erupts on the Sun - August 31

Sun Right Ascension

Posted by AT
Wikipedia defines Right ascension (RA) as the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth.  When paired with declination, these astronomical coordinates specify the location of a…
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Calculating Sun Declination

Posted by AT
Declination of the sun is the angle between the equator and a line drawn from Earth to Sun center to center. The declination angle varies seasonally due to 2 factors -- the tilt of the Earth on its axis and its rotation around the sun. If the Earth were not…
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Calculate Sunlight Hours

Posted by AT
The duration of sunlight follows a simple harmonic motion. It is periodic and repeats every year. In the Northern Hemisphere, the longest day is June 21, and the shortest is December 21. The averagelength of daylight is 12 h, and the variation from this average depends on the latitude. (Forexample,…
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Julain Day Calculation

Posted by AT
How To Calculate the Julian Day These are the steps: let a = (10000.0 * year) + (100.0 * (month)) + day;            note: a should be > -47120101 If month <= 2 then add 12 to month to become 13 or 14 and substract 1 from year             let…
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