Time standard
Sidereal Time
Time kept by the stars rather than the Sun — it measures the Earth's rotation relative to the fixed sky. A sidereal day is about four minutes shorter than a solar day, because the Earth must turn a little further each day to face the Sun again as it moves along its orbit.
Bodies, frames & concepts
Across celestial mechanics
Knowledge connections
- Associated withUniversal Time (UT1)
- Associated withEarth
- Associated withUniversal Time (UT1)
- Associated withApparent Solar Time
- Associated withRight Ascension
Sources
The primary and reference sources this topic draws on.
- US Naval ObservatoryUnited States Naval Observatory
Precise time, almanac data, Sun/Moon rise-set, and phases.