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Although ERA is intended to replace sidereal time, there is a need to maintain definitions for sidereal time during the transition, and when working with older data and documents. Similarly to mean solar time, every location on Earth has its own local sidereal time (LST), depending on the longitude of the point.
The relationship enabled astronomers to use the stars to measure sidereal time, which provided an accurate method for setting clocks. The equation of time was engraved on sundials so that clocks could be set using the Sun. In 1720, Joseph Williamson claimed to have invented a clock that showed solar time, fitted with a cam and differential ...
A domestic clock housed in a wooden case, it gives indications including the solar, mean and sidereal time around the world, the positions of the constellations and planets, and the appearance of Halley's Comet. [17] Sint-Truiden. The astronomical clock constructed by Kamiel Festraets between 1937 and 1942 is now housed in the Festraets Museum.
A sidereal rotation is the time it takes the Earth to make one revolution with rotation to the stars, approximately 23 hours 56 minutes 4 seconds. A mean solar day is about 3 minutes 56 seconds longer than a mean sidereal day, or 1 ⁄ 366 more than a mean sidereal day. In astronomy, sidereal time is used to predict when a star will reach its ...
The local hour angle (LHA) of an object in the observer's sky is = or = + where LHA object is the local hour angle of the object, LST is the local sidereal time, is the object's right ascension, GST is Greenwich sidereal time and is the observer's longitude (positive east from the prime meridian). [3]
A world clock is a clock which displays the time for various cities around the world. The display can take various forms: The display can take various forms: The clock face can incorporate multiple round analogue clocks with moving hands or multiple digital clocks with numeric readouts, with each clock being labelled with the name of a major ...
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As seen from above the Earth's north pole, a star's local hour angle (LHA) for an observer near New York. Also depicted are the star's right ascension and Greenwich hour angle (GHA), the local mean sidereal time (LMST) and Greenwich mean sidereal time (GMST). The symbol ♈︎ identifies the March equinox direction.