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Astronomy Answers: Position of the Sun; A Simple Expression for the Equation of Time; The Equation of Time; Equation of Time; Long-Term Almanac for Sun, Moon, and Polaris V1.11; Evaluating the Effectiveness of Current Atmospheric Refraction Models in Predicting Sunrise and Sunset Times
The United States Naval Observatory states "the Equation of Time is the difference apparent solar time minus mean solar time", i.e. if the sun is ahead of the clock the sign is positive, and if the clock is ahead of the sun the sign is negative. [6] [7] The equation of time is shown in the upper graph above for a period of slightly more than a ...
In Islamic astronomy, the passing of the Sun over the zenith of Mecca becomes the basis of the qibla observation by shadows twice a year on 27/28 May and 15/16 July. [ 5 ] [ 6 ] At a given location during the course of a day, the Sun reaches not only its zenith but also its nadir , at the antipode of that location 12 hours from solar noon .
Afternoon analemma photo taken in 1998–99 in Murray Hill, New Jersey, U.S., by Jack Fishburn.The Bell Laboratories building is in the foreground. In astronomy, an analemma (/ ˌ æ n ə ˈ l ɛ m ə /; from Ancient Greek ἀνάλημμα (analēmma) 'support') [a] 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 over ...
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
Celestial cartography, [1] uranography, [2] [3] astrography or star cartography [citation needed] is the aspect of astronomy and branch of cartography concerned with mapping stars, galaxies, and other astronomical objects on the celestial sphere. Measuring the position and light of charted objects requires a variety of instruments and techniques.
A star chart drawn 5000 years ago by the Indians in Kashmir, which also depict a supernova for the first time in human history. [7] The Nebra sky disk , a 30 cm wide bronze disk dated to 1600 BC, bears gold symbols generally interpreted as a sun or full moon, a lunar crescent, several stars including the Pleiades cluster and possibly the Milky Way.
In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. [1]