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 moon orbits the earth in a little under 28 earth days. It travels at almost 2,290 miles per hour. Coincidentally, the moon's rotation period is also a little under 28 days, meaning the same face points toward the earth during its entire orbit.The English word month is derived from moonth, which was how long the moon was observed to take to return to a specific phase. This is known as a sidereal month and is measured by observing how long it takes the Moon to pass a fixed star on the celestial sphere. 2  A synodic month is 29.53 days (29 days, 12 hours, 44 minutes, 2.8 seconds) and is measured from New Moon to New Moon.