a person or thing that retracts. Anatomy. a muscle that retracts an organ or protruded part. Surgery. an instrument or appliance for drawing back an impeding part, as the edge of an incision. a mechanism, device, or the like that regulates retraction: to adjust the retractor on a seat belt.
The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in approximately 27.323 days (a sidereal month). Earth and the Moon orbit about their barycentre (common center of mass), which lies about 4,600 km (2,900 mi) from Earth's center (about 34 of the radius of Earth).
It takes the moon about 27.3 days to orbit the earth, and lunations, i.e. full lunar phase cycles, i.e. how we see the moon from earth depending on where it is in orbit, are only about 29.5 days, Gregorian months, with the notable exception of February, are 30 and 31 days, so if there's a full moon super early in a month there's a good chance we'll get a second one before the month's end.