Greatest Elongation
This refers to the position of an inner planet (Mercury or Venus) when it is at maximum angular separation from the Sun as viewed from Earth i.e. how far from the Sun Mercury or Venus appears in our sky (see diagram 1).
Greatest Elongation - The position of Mercury or Venus when it has the greatest angular distance from the Sun ...
The greatest elongation for the two inferior planets, Mercury and Venus, occurs when the line from the Earth to the inferior planet is at a tangent to the Sun. That's when the Sun-Earth-(inferior)planet angle is greatest.
Venus at greatest elongation, 47° west of the Sun.
January 10
Mercury at greatest elongation 23° west of the Sun.
greatest elongation (NASA SP-7, 1965) The maximum angular distance of a body of the solar system from the sun, as observed from the earth. The direction of the body east or west of the sun is usually specified, as greatest elongation west.
The greatest elongation of such a body is its maximum angular distance from the sun before it starts back toward conjunction. The direction of the body east or west of the sun is usually specified, as greatest elongation east.
Since its greatest elongation (the angle made between the sun, the earth, and Venus) is 47°, it can never be seen much longer than 3 hr after sunset or 3 hr before sunrise. Venus revolves around the sun at a mean distance of c.
Because its orbit lies inside that of the Earth, Venus appears to move out from the Sun to a maximum distance, called greatest elongation, and then back towards the Sun.
The half-moon phase occurs at greatest elongation, when Mercury rises earliest before the Sun when at greatest elongation west, and setting latest after the Sun when at greatest elongation east (its separation from the Sun ranging from 18.
The first and last quarter phases occur at greatest elongation east and west, respectively, when Mercury's separation from the Sun ranges anywhere from 18.5° at perihelion to 28.3° at aphelion.
The greatest elongation of an inferior planet is its maximum angular distance from the Sun; at this time the planet sets (greatest elongation east) or rises (greatest elongation west) at the greatest time from sunset or sunrise.
Greatest Elongation refers to the largest separation of the planet from the Sun in our sky, either to the East, or to the West.
Elongation The angular separation of two bodies. The greatest elongation of Mercury and Venus occur when the planets are at their most angular distance from the Sun, as viewed from the Earth.
A Dictionary of Astronomy entry for greatest elongation
The Concise Oxford Dictionary of English Etymology entry for elongate
A Dictionary of Earth Sciences entry for elongation ratio
A Dictionary of Earth Sciences entry for elongation index ...
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.
Related category
- CELESTIAL MECHANICS ...
1. Using the data given in the text, calculate Venus's angular diameter, as seen by an observer on Earth, when the planet is (a) at its brightest, (b) at greatest elongation, and (c) at the most distant point in its orbit.
of a heavenly body from its centre of motion, as seen from the earth; designating especially the angular distance of the planet Mercury or Venus from the sun, or the apparent angle between a satellite and its primary. The greatest elongation of Venus ...
 See also: Elongation, Earth, Sun, Planet, Sky
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