List of longest-running U.S. primetime television series. This is a list of the longest running U.S. primetime television series, ordered by the number of broadcast seasons offered by a U.S. broadcast network or cable network in prime time on the show's original run. Broadcast syndication that could have been scheduled by local stations in prime time have been omitted.
The celestial equator is inclined by 23.4Â° to the ecliptic plane. The image shows the relations between Earth's axial tilt (or obliquity), rotation axis and plane of orbit. The celestial equator is a great circle on the imaginary celestial sphere, in the same plane as the Earth 's equator.In other words, it is a projection of the terrestrial equator out into space. As a result of the Earth's axial tilt, the celestial equator is inclined by 23.4Â° with respect to the ecliptic plane.At the poles, though, the celestial equator would be parallel to the horizon.) At all latitudes the celestial equator appears perfectly straight because the observer is only finitely far from the plane of the celestial equator but infinitely far from the celestial equator itself.
The celestial equator is the projection of Earth's equator onto the sky, and the North and South celestial poles (NCP and SCP) are the points on the sky directly above Earth's North and South poles. Instead of latitude, the North-South celestial coordinate is called Declination (Dec). As on the Earth, North-South positions are measured from the celestial equator, with the vertex at the Earth's center. Like latitude, it is measured in degrees, with negative values for positions South of the celestial equator. The equator is 0Âº Dec, and the South celestial pole is at -90Âº Dec. The East-West celestial coordinate is called Right Ascension (RA). Like longitude, East-West positions are measured on a parallel, with the vertex on the Earth's axis, from an arbitrary zero-point meridian on the fixed sky.