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).
The orbit of the Moon around the Earth is completed in approximately 27.32 days. The more precise figure is 27 days, 7 hours, 43 minutes, 11.6 seconds. The period between consecutive phases is longer, at 29.53 days, because the position of the Earth and Moon changes as Earth orbits around the Sun.