Definitions for "Sidereal Day"
The period of rotation of an object with respect to the stars. Compare this to a solar day, which is the period of rotation of an object with respect to the Sun. On Earth a sidereal day is 23 hours, 56 minutes and 4 seconds, while the solar day is 24 hours.
Twenty-four sidereal hours equal to 23 hours, 56 minutes and 4 seconds of clock time.
The length of a planet's rotation period relative to the stars.