How long does it take the moon to orbit the earth?

Question

We all know that the earth takes 364 days to orbit the sun. So how long does the moon take to orbit the earth

Answer 1

It depends on how you define "orbit".

If you define orbit to mean the time it takes the Moon to come back to the same point with respect to the Sun (new moon to new moon), that is a synodic month, which is 29.53059 days.

If you define orbit to mean the time it takes the Moon to come back to the same point with respect to a fixed star, that is a sideral month, which is 27.32166 days.

If you define orbit to mean the time it takes the Moon to come back to the same point with respect to the intersection of the equator and ecliptic, that is a tropical month, which is 27.32158 days.

If you define orbit to mean the time it takes the Moon to come back to its perigee, that is an anomalistic month, which is 27.55455 days.

If you define orbit to mean the time it takes the Moon to return to its ecliptical ascending node, that is a draconic month, which is 27.21222 days.

Answer 2

29.53 days. That's its synodic period, which is the amount of time it takes to go through its phases. This is by far the most commonly used figure. It has a 27.32 day sidereal revolution around the earth, with respect to the stars. The reason for the difference is because the earth orbits the sun. So the moon has to go farther around in order to complete it's entire phase cycle. There is NO relevant orbit which is 28 days. The closest to that is an anomalistic month, which is 27.55 days, and is essentially never used for anything. It's the amount of time between perigees. Edit: more explanation on that, since I'm not sure what frame of reference your physics question relates to. If you ignore the earth's orbit around the sun, the moon takes 27.32 days to go 360 degrees around us. In other words, the time it takes to cover 360 degrees of the celestial sphere. But since we orbit the sun, the moon has to travel farther than 360 degrees to reach the same point, with respect to the earth and sun. (It's about an extra 28 degrees). Since we notice phases much more than what stars we see the moon against, the phase cycle of 29.5 days is the one most commonly used. So if you are doing an orbital calculation based on mass and distance, or whatever, you should use the sidereal period. If the problem is related to phases or syzygies, use the synodic. Note: if the 27 and 1/3 day period (sidereal), was why we occasionally have 2 full moons in a month, we would have them a lot more often. The reason for "blue moons" is because of the 29.5 day synodic period. Because of this, we can never have a blue moon in February.

Answer 3

Your conclusion of 364 days for earth is wrong. It Should be 365 days and 6 hrs that is why we have a leap year every 4 years.
The moon is 28 days

Answer 4

ummm no it is 365 bc the leap year

Answer 5

It takes 29.5 days to orbit the Earth. This is also why we only see one side of the moon.

Answer 6

30.5 days.

The moon orbits the earth once a month. 365/12, hence the reason some months have 30 days and others have 31.

Answer 7

One month. That is where the word month comes from; a month is a Moon-th. And the actual value is about 29.5 days, but as has been pointed out above, it depends on how you measure it. So "about a month" is my answer.

Answer 8

One month. (30 days.) Ever notice how at one point during each month, the moon is full, and at another point it is not? Check with an astronomy specialist for a clearer explanation.

Answer 9

28 days. That's why you only get a full moon about once a month.

Answer 10

It takes about 29.53 days.