Quadrature
Related Category: Astronomy: General
in astronomy, arrangement of two celestial bodies at right angles to each other as viewed from a reference point.
quadrature
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Quadrature
(a) Elongation of a planet when it makes a 90° angle with the Sun as seen from Earth.
quadrature: Those points or moments at which a half moon is visible. More generally, it is the situation of two heavenly bodies when their longitudes differ by 90? [36] (tycho brahe) ...
Quadrature A configuration that two celestial bodies have apparent longitudes that differ by 90° as viewed from a third body.
Reflection nebula. A gas cloud illuminated by a nearby star.
Quadrature The position of a body (Moon or planet) such that its elongation is 90º or 270º; i.e. the Sun-Earth-body angle is 90º. (See diagram.)
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Radiant The position in the sky from which a meteor shower appears to radiate.
Quadrature
a point in the orbit of a superior planet where it appears at right angles to the Sun as seem from Earth.
Quadrature. The position of the Moon or another planet when it is at right angles to the Sun as seen from Earth. An example would be when the Moon is seen at First or Last Quarter phases.
The Quadrature of the Parabola is a treatise on geometry, written by Archimedes in the 3rd century B.C.
Quadrature: (Dec)
A planet is in quadrature when its longitude differs from that of the sun by 90 degrees.
Quadrature
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The Sun, Earth and Solar System body lie at the corners of a right-angled triangle ...
quadrature - (n.)
The configuration where a superior planet or the moon is 90 degrees away from the sun, as seen from the earth.
quantum - (n.) ...
quadrature (NASA Thesaurus / NASA SP-7, 1965) 1. An elongation of 90 degrees, usually specified as east or west in accordance with the direction of the body from the sun. The moon is at quadrature at first and last quarters. Compare conjunction.
In-phase and quadrature (I&Q) components
The term in-phase is also found in the context of communication signals: ...
A planet at western quadrature will be near your meridian at sunrise. If the Sun had a right ascension of 10h the planet at western quadrature would have a right ascension of 4hr.
This is difficult stuff! ...
First quarter occurs when the waxing moon is at east quadrature; last quarter when the waning moon is at west quadrature.
Caves, Thorne invented the back-action-evasion approach to quantum nondemolition measurements of the quadrature amplitudes of harmonic oscillators---a technique applicable both in gravitational wave detection and quantum optics.
quadrature when a superior planet appears at right angles to the Sun as seen from the Earth
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Microwave dishes on satellites, telephone exchanges and TV stations usually use quadrature amplitude modulation (QAM). QAM sends data by changing both the phase and the amplitude of the radio signal.
The quadrature locations are sort of like the quarter phases of the Moon, at least in terms of the questions of "when do they rise," "when do they set," etc.
He found that, although the two inequalities found by Hipparchus and Ptolemy correctly represented the moon's longitude near conjunction and opposition, and also at the quadratures, it left a large outstanding error at the octants, ...
The phase angle or terminator will increase from the time we first see Mars rising early in the morning sky until a week or two before western quadrature. After quadrature the phase will decrease until it nearly disappears around opposition.
When a superior planet is at quadrature, it is on our celestial meridian at sunrise or sunset.
Quadratures are usually tabulated with respect to the Sun as viewed from the center of the Earth. [S92]
(c) A means of combining errors or noise by summing the "square" of the values and then taking the "square root". [McL97] ...
Superior planets can only ever appear as full or gibbous. In the case of Mars, at quadrature 87 per cent of the planet is illuminated as seen from Earth; the more distant planets have increasingly greater minimum phases.
aspect
The apparent position of any of the planets or the Moon relative to the Sun, as seen from Earth. The four main aspects are conjunction, greatest elongation, opposition, and quadrature.
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Hipparchus was dissatisfied however, for, as he appreciated, the errors at quadrature (when the Moon stands at first and last quarters) were too great.
 See also: Earth, Planet, Sun, Second, Distance
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