The equatorial coordinate system is a widely-used method of specifying the positions of celestial objects. It may be implemented in spherical or rectangular coordinates, both defined by an origin at the center of the Earth, a fundamental plane consisting of the projection of the Earth's equator onto the celestial sphere (forming the celestial equator), a primary direction towards the vernal equinox, and a right-handed convention.
The origin at the center of the Earth means the coordinates are geocentric, that is, as seen from the center of the Earth as if it were transparent and nonrefracting. The fundamental plane and the primary direction mean that the coordinate system, while aligned with the Earth's equator and pole, does not rotate with the Earth, but remains relatively fixed against the background stars. A right-handed convention means that coordinates are positive toward the north and toward the east in the fundamental plane.
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Famous quotes containing the word system:
“The system was breaking down. The one who had wandered alone past so many happenings and events began to feel, backing up along the primal vein that led to his center, the beginning of hiccup that would, if left to gather, explode the center to the extremities of life, the suburbs through which one makes one’s way to where the country is.”
—John Ashbery (b. 1927)