Galactic coordinate system

galactic coordinate system
The coordinate system in which a celestial object’s position on the celestial sphere is described in relation to the structure of the Milky Way galaxy. ◇ An object’s galactic longitude is measured along the galactic equator, a great circle on the celestial sphere that follows the band of the Milky Way. The galactic equator, also called the galactic circle, is inclined at an angle of approximately 62° to the celestial equator; distances are measured along it beginning at a point in the constellation Sagittarius lying in the direction of the Milky Way’s nucleus. The galactic poles are the two points where a perpendicular line through the middle of the plane of the galactic equator intersect the celestial sphere. ◇ An object’s galactic latitude is measured in degrees north or south of the galactic equator toward the galactic poles.


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  • Galactic-equator

    noun, Astronomy. 1. the great circle on the celestial sphere that is equidistant from the galactic poles, being inclined approximately 62° to the celestial equator and lying about one degree north of the center line of the Milky Way. noun 1. the great circle on the celestial sphere containing the galactic plane

  • Galactic halo

    noun 1. (astronomy) a spheroidal aggregation of globular clusters, individual stars, dust, and gas that surrounds the Galaxy galactic halo A large, spherical region of relatively dust-free space surrounding a spiral galaxy such as the Milky Way. The inner regions of the galactic halo contain globular clusters of very old stars, while the outer regions […]

  • Galactic-latitude

    noun, Astronomy. 1. the angular distance from the galactic equator of a point on the celestial sphere.

  • Galactic-longitude

    noun, Astronomy. 1. the angular distance in degrees measured eastward in the galactic plane from a radius drawn from the earth as center to the constellation Sagittarius.
