equinoctial line

equinoctial line
    n 1: the great circle on the celestial sphere midway between the
         celestial poles [syn: {celestial equator}, {equinoctial
         circle}, {equinoctial line}, {equinoctial}]
    

Equator \E*qua"tor\, n. [L. aequator one who equalizes: cf. F.
   ['e]quateur equator. See {Equate}.]
   1. (Geog.) The imaginary great circle on the earth's surface,
      everywhere equally distant from the two poles, and
      dividing the earth's surface into two hemispheres.
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   2. (Astron.) The great circle of the celestial sphere,
      coincident with the plane of the earth's equator; -- so
      called because when the sun is in it, the days and nights
      are of equal length; hence called also the {equinoctial},
      and on maps, globes, etc., the {equinoctial line}.
      [1913 Webster]

   {Equator of the sun} or {Equator of a planet} (Astron.), the
      great circle whose plane passes through through the center
      of the body, and is perpendicular to its axis of
      revolution.

   {Magnetic equator}. See {Aclinic}.
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Equinoctial \E`qui*noc"tial\, a. [L. aequinoctials, fr.
   aequinoctium equinox: cf. F. ['e]quinoxial. See {Equinox}.]
   1. Pertaining to an equinox, or the equinoxes, or to the time
      of equal day and night; as, the equinoctial line.
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   2. Pertaining to the regions or climate of the equinoctial
      line or equator; in or near that line; as, equinoctial
      heat; an equinoctial sun.
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   3. Pertaining to the time when the sun enters the equinoctial
      points; as, an equinoctial gale or storm, that is, one
      happening at or near the time of the equinox, in any part
      of the world.
      [1913 Webster]

   {Equinoctial colure} (Astron.), the meridian passing through
      the equinoctial points.

   {Equinoctial line} (Astron.), the celestial equator; -- so
      called because when the sun is on it, the nights and days
      are of equal length in all parts of the world. See
      {Equator}.
      [1913 Webster]

            Thrice the equinoctial line
            He circled.                           --Milton.

   {Equinoctial points} (Astron.), the two points where the
      celestial and ecliptic intersect each other; the one being
      in the first point of Aries, the other in the first point
      of Libra.

   {Equinoctial time} (Astron.) reckoned in any year from the
      instant when the mean sun is at the mean vernal
      equinoctial point.
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