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Right ascension (abbreviated RA; symbol α) is 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. [ 1 ] When paired with declination, these astronomical coordinates specify the location of a point on the ...
The longitude of the ascending node (bright green) as a part of a diagram of orbital parameters. The longitude of the ascending node, also known as the right ascension of the ascending node, is one of the orbital elements used to specify the orbit of an object in space. Denoted with the symbol Ω, it is the angle from a specified reference ...
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]
Animation showing the difference between a sidereal day and a solar day. Sidereal time ("sidereal" pronounced / saɪˈdɪəriəl, sə -/ sy-DEER-ee-əl, sə-) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky.
Alternatively to right ascension, hour angle (abbreviated HA or LHA, local hour angle), a left-handed system, measures the angular distance of an object westward along the celestial equator from the observer's meridian to the hour circle passing through the object. Unlike right ascension, hour angle is always increasing with the rotation of Earth.
The galactic longitude (l) runs from the Sun upwards in the image through the center of the galaxy. The galactic latitude (b) is perpendicular to the image (i.e. coming out of the image) and also centered on the Sun. The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary ...
The equation of time is obtained by substituting the result of the right ascension calculation into an equation of time formula. Here Δ t ( M ) = M + λ p − α [ λ ( M )] is used; in part because small corrections (of the order of 1 second), that would justify using E , are not included, and in part because the goal is to obtain a simple ...
Derivative of −Δt, the so-called Equation of time. The axis on the right shows the length of the solar day, also called the synodic day. Because of the variation in the rate at which the sun's right ascension changes, the days of longest and shortest daylight do not coincide with the solstices for locations very close to the equator. At the ...