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  2. Ecliptic coordinate system - Wikipedia

    en.wikipedia.org/wiki/Ecliptic_coordinate_system

    Ecliptic longitude Ecliptic longitude or celestial longitude (symbols: heliocentric l, geocentric λ) measures the angular distance of an object along the ecliptic from the primary direction. Like right ascension in the equatorial coordinate system, the primary direction (0° ecliptic longitude) points from the Earth towards the Sun at the ...

  3. Ecliptic - Wikipedia

    en.wikipedia.org/wiki/Ecliptic

    Spherical coordinates, known as ecliptic longitude and latitude or celestial longitude and latitude, are used to specify positions of bodies on the celestial sphere with respect to the ecliptic. Longitude is measured positively eastward [6] 0° to 360° along the ecliptic from the March equinox, the same direction in which the Sun appears to ...

  4. Solar longitude - Wikipedia

    en.wikipedia.org/wiki/Solar_longitude

    Solar longitude, commonly abbreviated as Ls, is the ecliptic longitude of the Sun, i.e. the position of the Sun on the celestial sphere along the ecliptic.It is also an effective measure of the position of the Earth (or any other Sun-orbiting body) in its orbit around the Sun, [1] usually taken as zero at the moment of the vernal equinox. [2]

  5. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    The geocentric ecliptic system was the principal coordinate system for ancient astronomy and is still useful for computing the apparent motions of the Sun, Moon, and planets. [3] It was used to define the twelve astrological signs of the zodiac , for instance.

  6. Almagest - Wikipedia

    en.wikipedia.org/wiki/Almagest

    The ecliptic longitudes are given in terms of a zodiac sign and a number of degrees and fractions of a degree. The zodiac signs each represent exactly 30°, starting with Aries representing longitude 0° to 30°. The degrees are added to the lower limit of the 30-degree range to obtain the longitude.

  7. True longitude - Wikipedia

    en.wikipedia.org/wiki/True_longitude

    In celestial mechanics, true longitude is the ecliptic longitude at which an orbiting body could actually be found if its inclination were zero. Together with the inclination and the ascending node, the true longitude can tell us the precise direction from the central object at which the body would be located at a particular time.

  8. First point of Aries - Wikipedia

    en.wikipedia.org/wiki/First_point_of_Aries

    It is on the celestial equator at both the left and right extremes of the sky chart, with the ecliptic (the orange dotted sine curve) passing through it. The first point of Aries , also known as the cusp of Aries , is the location of the March equinox (the vernal equinox in the northern hemisphere, and the autumnal equinox in the southern ...

  9. Position of the Sun - Wikipedia

    en.wikipedia.org/wiki/Position_of_the_Sun

    The mean longitude of the Sun, corrected for the aberration of light, is: = + The mean anomaly of the Sun (actually, of the Earth in its orbit around the Sun, but it is convenient to pretend the Sun orbits the Earth), is: