Celestial sphere

celestial sphere"The apparent sphere of infinite radius, having Earth as its center. It is upon the "inner surface" of this sphere that all heavenly bodies, the ecliptic, and the celestial equator appear.

CELESTIAL SPHERE The apparent sphere of infinite radius having the earth as its center. All heavenly bodies (planets, stars, etc.) appear on the "inner surface" of this sphere and the sun moves along the ecliptic.

CELESTIAL EQUATOR The projection of the plane of the geographical equator upon the celestial sphere. CELESTIAL SPHERE The apparent sphere of infinite radius having the earth as it center.

sunrise and sunset. 4) Astronomical horizon (also called sensible horizon, real horizon): the plane that passes through the observer's eye and is perpendicular to the zenith at that point; or, the intersection of that plane with the celestial sphere ...

"NadirThe point on any given observer's celestial sphere diametrically opposite of one's zenith.NAMThe operational North American Meso (NAM, formerly Eta) is run four times per day (00,06,12,18Z), all cycles run to 84-h.

Zenith, Nadir, and the Celestial Sphere "Zenith," "nadir," and the "celestial sphere" are terms used by meteorologists, climatologists, and other scientists with reference to astronomical positions.

In the field of astronomy, the sky is also called the celestial sphere. This is an imaginary dome where the sun, stars, planets, and the moon are seen to be travelling. The celestial sphere is divided into regions called constellations.

The angle (in degrees) between the horizon and a point above the local horizon in the celestial sphere, measured along the great circle that passes through both the zenith and the point in question.
escape velocity ...

ECLIPTIC
The sun's apparent path across the sky that tracks a circle through the celestial sphere.
ECOLOGY
The study of the relationships between living organisms and their environment.

Solstice: Either of the two times per year when the sun is at its greatest angular distance from the celestial equator: about June 21 (the Northern Hemisphere summer solstice), when the sun reaches its northernmost point on the celestial sphere, ...

See also: Earth, Surface, Air, Weather, Light