ecliptic

e·clip·tic  (-klptk)

n.

1. The intersection plane of the earth's orbit with the celestial sphere, along which the sun appears to move as viewed from the earth.

2. A great circle inscribed on a terrestrial globe inclined at an approximate angle of 23°27 to the equator and representing the apparent motion of the sun in relation to the earth during a year.

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[Middle English ecliptik, from Medieval Latin (lnea) eclptica, ecliptic (line), from Latin eclpticus, of an eclipse, from Greek ekleiptikos, from ekleipein, to fail to appear; see eclipse.]

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ecliptic [ɪˈklɪptɪk]

n

1. (Astronomy) Astronomy

a.  the great circle on the celestial sphere representing the apparent annual path of the sun relative to the stars. It is inclined at 23.45° to the celestial equator. The poles of the ecliptic lie on the celestial sphere due north and south of the plane of the ecliptic

b.  (as modifier) the ecliptic plane

2. (Mathematics & Measurements / Navigation) an equivalent great circle, opposite points of which pass through the Tropics of Cancer and Capricorn, on the terrestrial globe

adj

(Astronomy) of or relating to an eclipse

ecliptically  adv

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ecliptic  (-klptk)

The great circle on the celestial sphere that represents the Sun's apparent path among the background stars in one year. The northernmost point this path reaches on the celestial sphere is the Tropic of Cancer, its southernmost point is the Tropic of Capricorn, and it crosses the celestial equator at the points of vernal and autumnal equinox. The plane of the ecliptic is the imaginary plane that intersects the celestial sphere along the ecliptic, and the north and south ecliptic poles are the points where a perpendicular line through the middle of this plane intersect the sphere. The plane of the ecliptic corresponds to the plane in which the Earth orbits the Sun. If the Earth's axis were not tilted, the ecliptic would be identical to the celestial equator and the ecliptic poles identical to the celestial poles. In this case, the Sun's path would not move northward or southward from the equator during the year. As it is, the plane of the celestial equator is tilted 23.45° to the plane of the ecliptic, corresponding to the tilt of the Earth's axis with respect to its orbital plane, giving the Sun its apparent northward and southward movement among the background stars. See illustration at celestial sphere.

Thesaurus

Noun

1.

ecliptic - the great circle representing the apparent annual path of the sun; the plane of the Earth's orbit around the sun; makes an angle of about 23 degrees with the equator; "all of the planets rotate the sun in approximately the same ecliptic" great circle - a circular line on the surface of a sphere formed by intersecting it with a plane passing through the center