Galactic coordinate system,
astronomical coordinate system in which the principal axis is the galactic equator (the intersection of the plane of the Milky Way with the
celestial sphere) and the reference points are the north galactic pole and the zero point on the galactic equator; the coordinates of a celestial body are its galactic longitude and galactic latitude. In the IAU galactic coordinate system, introduced in 1958 by the International Astronomical Union, the zero point on the galactic equator has the equatorial coordinates R.A. 17h39.3m and Dec. −28°55'; this lies in the direction of the center of our galaxy, the Milky Way.
The distance between the sun and the earth varies because the earth travels in an elliptical rather than circular orbit. The distance is r...
Galaxy, a massive ensemble of hundreds of millions of stars, all gravitationally interacting, and orbiting about a common center. Astronomer...