Post-concussion syndrome. Post-concussion syndrome, also known as postconcussive syndrome or PCS, is a set of symptoms that may continue for weeks, months, or a year or more after a concussion â a mild form of traumatic brain injury (TBI).
The Equatorial (Celestial) Coordinate System. Equatorial coordinates, also called simply celestial coordinates, are the standard coordinate system for the sky. It is meant for the fixed sphere of the stars within which the Earth and Sun move.
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.