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).
Ignoring the earth position relative to our sun, the moon takes 27 days 7 hours and 43 minutes to orbit the earth - the sidereal orbit (orbit relative to background stars). Duâ¦ring this time, the earth has progressed around the sun a little, on its orbit around the sun. For the moon to get back to exactly the right phase, it takes a little longer, 29 days, 12 hours and 44 minutes in total from full moon to the next full moon. This is known as the synodic period. The moon will have made just over one orbit relative to the background stars, and will have moved round slightly to be in front of some different stars to those at the previous full moon.