draconic month

The draconic month, also known as the nodical month or draconic period, is an astronomical term for the time it takes the Moon to orbit from one ascending node to the same ascending node. An ascending node is where the Moon's orbit crosses the ecliptic (the Sun's apparent path) from south to north. This period averages 27.212220 days, or 27 days, 5 hours, 5 minutes, and 35.8 seconds of mean solar time. The draconic month is one of several ways to measure the Moon's orbital period, differing from the synodic month (the time for the Moon to complete a cycle of phases as seen from Earth) and the sidereal month (the time to return to the same position relative to the stars).123