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