How long does it take for the moon to complete one full revolution around the Earth?

A. 1 day

B. 365 days

C. 29.5 years

D. 1 year

365 Days. That's why our year is so long.

To be honest with you It only takes 27 days, 7 hours, and 43 minutes for our Moon to complete one full orbit around Earth. This is called the sidereal month, and is measured by our Moon's position relative to distant "fixed" stars. However, it takes our Moon about 29.5 days to complete one cycle of phases (from new Moon to new Moon).