Synonym: Sidereal Lunar Month
The sidereal month is the time it takes for the moon to make one complete revolution around the earth; or the time it takes for the moon to reach the same position on the hour circle with respect to the fixed stars.
The sidereal month is 27 days, 7 hours and 43 minutes and is therefore slightly shorter than the synodic month or typical calendar month.
- The Sidereal and Synodic Months - Animation (Freedman and Kaufmann, 2004)
- Sidereal and Synodic Periods of the Moon (Illustration)