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  2. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    Although ERA is intended to replace sidereal time, there is a need to maintain definitions for sidereal time during the transition, and when working with older data and documents. Similarly to mean solar time, every location on Earth has its own local sidereal time (LST), depending on the longitude of the point.

  3. Sidereal year - Wikipedia

    en.wikipedia.org/wiki/Sidereal_year

    The sidereal year differs from the solar year, "the period of time required for the ecliptic longitude of the Sun to increase 360 degrees", [2] due to the precession of the equinoxes. The sidereal year is 20 min 24.5 s longer than the mean tropical year at J2000.0 (365.242 190 402 ephemeris days) .

  4. Astronomical clock - Wikipedia

    en.wikipedia.org/wiki/Astronomical_clock

    A domestic clock housed in a wooden case, it gives indications including the solar, mean and sidereal time around the world, the positions of the constellations and planets, and the appearance of Halley's Comet. [17] Sint-Truiden. The astronomical clock constructed by Kamiel Festraets between 1937 and 1942 is now housed in the Festraets Museum.

  5. Universal Time - Wikipedia

    en.wikipedia.org/wiki/Universal_Time

    In 1928, the term Universal Time (UT) was introduced by the International Astronomical Union to refer to GMT, with the day starting at midnight. [8] The term was recommended as a more precise term than Greenwich Mean Time, because GMT could refer to either an astronomical day starting at noon or a civil day starting at midnight. [9]

  6. Sidereal and tropical astrology - Wikipedia

    en.wikipedia.org/wiki/Sidereal_and_tropical...

    Sidereal astrology accounts for the Earth's axial precession and maintains the alignment between signs and constellations via corrective systems known as ayanamsas (Sanskrit: 'ayana' "movement" + 'aṃśa' "component"), whereas tropical astrology, to reiterate, is based upon the seasonal cycle of the Northern hemisphere and does not take axial ...

  7. Rotation period (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Rotation_period_(astronomy)

    27.321661 days [7] (equal to sidereal orbital period due to spin-orbit locking, a sidereal lunar month) 27 d 7 h 43 m 11.5 s: 29.530588 days [7] (equal to synodic orbital period, due to spin-orbit locking, a synodic lunar month) none (due to spin-orbit locking) Mars: 1.02595675 days [3] 1 d 0 h 37 m 22.663 s: 1.02749125 [8] days: Ceres: 0.37809 ...

  8. Time standard - Wikipedia

    en.wikipedia.org/wiki/Time_standard

    A sidereal rotation is the time it takes the Earth to make one revolution with rotation to the stars, approximately 23 hours 56 minutes 4 seconds. A mean solar day is about 3 minutes 56 seconds longer than a mean sidereal day, or 1 ⁄ 366 more than a mean sidereal day. In astronomy, sidereal time is used to predict when a star will reach its ...

  9. Sidereal - Wikipedia

    en.wikipedia.org/wiki/Sidereal

    Sidereal, meaning "of the stars", may refer to: Sidereal time; Sidereal day; Sidereal month; Sidereal year; Sidereal period of an object orbiting another astronomical object; Sidereal and tropical astrology; See also. Sideral (disambiguation)