# Moon Orbit Earth How Long

It might seem like a trivial question, and most people would probably say 28 days. But, it isn’t so simple.

On average it takes 27.322 days (that’s a sidereal month, and a nice number of significant figures for something astronomical, especially when defining the day is not so clear cut) for the Moon to complete one orbit around Earth. However, the number of days between Full Moons is about 29.5306 days as the Moon has to “catch up with the sun” as it were. So, the actual number of days may differ from the average number by more than a half day. From one Full Moon to the next, the number of days in one lunation can vary between 29.272 and 29.833 days (another nice clutch of significant figures).

The age and apparent size of the Full Moon vary in a cycle of just under 14 synodic months, which is called the Full moon cycle.

The true Full Moon may differ from the calculated peak by up to about 14.5 hours, due to the normal irregularity in the Moon’s Keplerian orbit, and due to the periodic perturbations in that orbit caused by the Sun, the equatorial bulge of the Earth, and the proximity of other planets.

Anyway, I hope this little snippet answer the search query a recent visitor plugged into the sciencebase search box – “moon orbit earth how long”

## 9 thoughts on “Moon Orbit Earth How Long”

1. Ashley says:

Thank yeww i needed this for class!
it was a huge help <3

2. Kimiko says:

Thanks i’m in class and this really help thanks a lot

3. koalalover6 says:

I’m doing a science project and this really helped me!! Thanks!!

4. Danielle says:

I need how many days the moon orbits the earth for my math class. Thank you it help me alot.

5. Jason says:

I woke up at 4am this morning, needing to know the answer. Brilliant Thank you.

6. Dalton Carey says:

this was a very good article and it help me with a school progect. i got useful information.

7. sciencebase says:

Good point!

8. AnyMouse says:

Another answer to that phrase is “4.533 billion years”.
How long the Moon has been in orbit.