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blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The direction straight up.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The set of all possible directions with altitude 60°
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The path of the Sun (over a year) on the celestial sphere.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The vertical circle including the observer's zenith, and north and south points on the horizon.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The great circle formed by the intersection of the celestial sphere with a plane perpendicular to the line from an observer to the zenith.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The most important of all circles of reference.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - Any great circle on the celestial sphere which passes through the north and south celestial poles.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - Any great circle passing through both the observer's zenith and nadir.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The angle
*eastward*along the celestial equator from the vernal equinox to the foot of the hour circle through the object. blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The angle from the north point of the horizon
*clockwise*to the foot of the vertical circle through the object. blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - Where sky and ground meet.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The farthest points from the celestial equator.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The circle along which declination is measured.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The point where the Sun crosses the celestial equator from south to north each year.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The angle between a object on the celestial sphere and the celestial equator.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - Any circle on the surface of a sphere which divides the sphere into two equal parts.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The angle from the horizon along the vertical circle to the object.
blank altitude azimuth celestial equator celestial pole celestial sphere declination diurnal circle ecliptic great circle horizon hour angle hour circle meridian nadir right ascension small circle vernal equinox vertical circle zenith - The path that a star makes in the sky over a day.