The Moon takes about 27.3 days to orbit (and rotate once relative to the stars) around Earth, and about 29.5 days to go from one new moon to the next.

Quick Scoop

  • The Moon completes one orbit around Earth in about 27.3 days (this is called a sidereal month).
  • The cycle of Moon phases (new moon to new moon) takes about 29.5 days (a synodic month).
  • The Moon also rotates once on its axis in about 27.3 days , which is why we always see nearly the same side.
  • Its orbit is slightly elliptical , so distance and speed change a bit, but the overall timing stays close to these values.

Why two different numbers?

  • The 27.3-day period is measured against the background stars : how long the Moon takes to make a true loop around Earth.
  • The 29.5-day period is measured by what we see in the sky : the time from one new moon to the next, which is longer because Earth is moving around the Sun while the Moon orbits us.

A simple way to picture it: imagine you and a friend walking around a track while someone runs circles around you; because you’re both moving, the runner has to go a little farther each lap to line up with you the same way again.

TL;DR:

  • Orbit around Earth: about 27.3 days.
  • Full phase cycle (new moon to new moon): about 29.5 days.

Information gathered from public forums or data available on the internet and portrayed here.