Sideral day definition of Sideral day in the Free Online Encyclopedia.

sidereal time (ST), time time, sequential arrangement of all events, or the interval between two events in such a sequence. The concept of time may be discussed on several different levels: physical, psychological, philosophical and scientific, and biological.
..... Click the link for more information. measured relative to the fixed stars; thus, the sidereal day is the period during which the earth completes one rotation on its axis so that some chosen star appears twice on the observer's celestial meridian celestial meridian, vertical circle passing through the north celestial pole and an observer's zenith . It is an axis in the altazimuth coordinate system .
..... Click the link for more information. . Because the earth moves in its orbit about the sun, the sidereal day is about 4 min shorter than the solar day (see solar time solar time, time defined by the position of the sun. The solar day is the time it takes for the sun to return to the same meridian in the sky. Local solar time is measured by a sundial .
..... Click the link for more information. ). Thus, a given star will appear to rise 4 min earlier each night, so that different stars are visible at different times of the year. The local sidereal time of an observer is equal to the hour angle hour angle, in astronomy, a coordinate in the equatorial coordinate system . The hour angle of a celestial body is the angular distance, expressed in hours, minutes, and seconds (one hour equals 15 degrees), measured westward along the celestial equator from the
..... Click the link for more information. of the vernal equinox.

sidereal time [sī′dir·ē·əl ′tīm]

(astronomy)

Time based on diurnal motion of stars; it is used by astronomers but is not convenient for ordinary purposes.

sidereal time (redirected from Sideral day)

sidereal time
(redirected from Sideral day)