galactic coordinate system

American  

noun

1. Astronomy. the coordinate system used to describe the position of a celestial object on the celestial sphere in terms of its galactic longitude and galactic latitude.

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galactic coordinate system Scientific  

1. 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.

2. ◆ 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.

3. ◆ An object's galactic latitude is measured in degrees north or south of the galactic equator toward the galactic poles.

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