Definition that contains celestial sphere
- direct moving from west to east on the celestial sphere; or--for planets--around the sun in the same direction as the Earth
- pole one of two points of intersection of the Earth's axis and the celestial sphere
- ra (astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere
- horizon the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth
- dec (astronomy) the angular distance of a celestial body north or to the south of the celestial equator; expressed in degrees; used with right ascension to specify positions on the celestial sphere
- apex the point on the celestial sphere toward which the sun and solar system appear to be moving relative to the fixed stars
- retrograde moving from east to west on the celestial sphere; or--for planets--around the sun in a direction opposite to that of the Earth
- declination (astronomy) the angular distance of a celestial body north or to the south of the celestial equator; expressed in degrees; used with right ascension to specify positions on the celestial sphere
- right ascension (astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere
- celestial horizon the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth