section_path: Definitions/Sidereal day
section_name: Sidereal day
paragraph_text: Sidereal day
  
  A sidereal day or stellar day is the span of time it takes for the Earth to make one entire rotation with respect to the celestial background or a distant star (assumed to be fixed). Measuring a day as such is used in astronomy. A sidereal day is about 4 minutes less than a solar day of 24 hours (23 hours 56 minutes and 4.09 seconds), or 0.99726968 of a solar day of 24 hours. There are about 366.2422 stellar days in one mean tropical year (one stellar day more than the number of solar days).
  
  Besides a stellar day on Earth, other bodies in the Solar System have day times, the durations of these being: