rotation of moon

[spunnery]

if i say moon is not rotating in its own axis,is there any body to oppose me??? with explanation of synchronous rotation.

 

if a car is moving along a circular path,and you are standing at the centere of this circle. Do you say the car is rotating on its own axis??

 

of course everybody will agree that it is making a revolution around u.but no body will say it is rotating in its own axis.

 

 

during this revolution u can see only one side of the car,is it true in the case of moon also ? or am i wrong????

[Klaynos]

Are you talking about it's orbit or it's rotation?

 

Rotation is how it's spinning like a basket ball on a finger. And orbit is it's motion around the earth.

[swansont]

By definition, the moon rotates on its axis, once per revolution. The car in your example is, too. Just because one might not realize this does not make it untrue.

[insane_alien]

if the car wasn't spinning on its access then you would see all sides of the car rather than the one side and you would need some fancy suspension/axle/drivetrain to make it possible as well.

[spunnery]

By definition, the moon rotates on its axis, once per revolution. The car in your example is, too. Just because one might not realize this does not make it untrue.

if we can say that the car is rotating in its own axis ,then do you admit that youll say ,a hammer throw ball is rotating on its own axis instead of saying that it is rotating with thrower as axis ?

[swansont]

if we can say that the car is rotating in its own axis ,then do you admit that youll say ,a hammer throw ball is rotating on its own axis instead of saying that it is rotating with thrower as axis ?

 

I would probably not say that without knowing what a "hammer throw ball" is.

 

How you describe motion depends on what coordinate system you choose. You would probably not look at the moon rotation of you were looking at the earth-moon system, since talking about the orbit and phase-lock adequately describes that, and already includes the behavior of the moon. But when you ask the question of whether the moon rotates on its own axis, you are looking solely at the moon, and the answer to that is "yes."

[spunnery]

I would probably not say that without knowing what a "hammer throw ball" is.

 

How you describe motion depends on what coordinate system you choose. You would probably not look at the moon rotation of you were looking at the earth-moon system, since talking about the orbit and phase-lock adequately describes that, and already includes the behavior of the moon. But when you ask the question of whether the moon rotates on its own axis, you are looking solely at the moon, and the answer to that is "yes."

rather, i will say moon is not rotating on its own axis but rotating around an axis which pass through the centre of earth.

[insane_alien]

its revolving around an axis that goes through the earth.

its rotating around its own axis.

 

a quick dictionary check should point out the differences between those words.

its been the cause of a few physics class showdowns.

[Sisyphus]

Further, it is not just a matter of the Moon revolving around the Earth. Both of them together revolve around their common center of gravity. Because the Earth is much larger, that center is actually inside the Earth, but it's certainly not the center. The Moon affects the Earth just as much as the Earth affects the Moon.

[spunnery]

Further, it is not just a matter of the Moon revolving around the Earth. Both of them together revolve around their common center of gravity. Because the Earth is much larger, that center is actually inside the Earth, but it's certainly not the center. The Moon affects the Earth just as much as the Earth affects the Moon.

yes,you come to the point.So moon is like sitting on a merry go round with earth as almost center.now my question is wheather you will see earth rising & setting as viewed from moon??

[Edtharan]

if we can say that the car is rotating in its own axis ,then do you admit that youll say ,a hammer throw ball is rotating on its own axis instead of saying that it is rotating with thrower as axis ?

The moon is not a single object. It is in fact made up of lots and lots of atoms, which they themselves are made up of electrons and quarks, etc.

 

A Hammer throw is made up of the atoms of the thrower and the hammer. Asking whether the hammer is rotating about it's axis or the the thrower is like asking if the atoms of the moon are rotating around the moons axis or their common axis.

 

It is both, the axis are the same.

[Sisyphus]

yes,you come to the point.So moon is like sitting on a merry go round with earth as almost center.now my question is wheather you will see earth rising & setting as viewed from moon??

 

No, you don't. It stays in one place in the sky. But I don't see how that's "the point."

[spunnery]

No, you don't. It stays in one place in the sky. But I don't see how that's "the point."

 

if earth stays in one oplace in the sky ,doesn't it means moon is not rotating in its own axis.if moon rotate a degree,earth will move accordingly on the sky. So why we are taught as moon is rotating on its own axis?????

[Sisyphus]

Because the Earth revolves about the Moon at the same rate that the Moon is rotating, so it keeps up. You gave an example of a hammer thrower. For him, the hammer is always directly in front of him, because he is rotating at the same rate that the hammer is revolving around him. The thrower is obviously rotating, though. It is all just a matter of perspective.

 

(By the way, we appreciate good punctuation and capitalization here. It's easier to read, and makes you seem less like a crazy person.)

[swansont]

if earth stays in one oplace in the sky ,doesn't it means moon is not rotating in its own axis.if moon rotate a degree,earth will move accordingly on the sky. So why we are taught as moon is rotating on its own axis?????

 

 

No, because the earth is not in a fixed place. If the moon rotates and the earth moves synchronously (in that coordinate system), then it will stay in a fixed place.

 

You need to make the measurement with respect to something not in the rotating system, like any star (other than the sun).

[D H]

You need to make the measurement with respect to something not in the rotating system, like any star (other than the sun).

 

The sun works, too (kind of). A "day" on the moon (one cycle of sunlight and darkness) last about 29.5 of our earthly days. It takes a bit less than 27.5 days for the moon to rotate with respect to the fixed stars.

[spunnery]

The sun works, too (kind of). A "day" on the moon (one cycle of sunlight and darkness) last about 29.5 of our earthly days. It takes a bit less than 27.5 days for the moon to rotate with respect to the fixed stars.

The day and night of moon is not caused by the rotation of moon on its own axis,but because it is moving in a circular path(not around sun) ,which can be called epicycle (???).This explanation is not enough to proove(say-it doesn't help to visualise ) the rotation of moon.

[spunnery]

Because the Earth revolves about the Moon at the same rate that the Moon is rotating, so it keeps up. You gave an example of a hammer thrower. For him, the hammer is always directly in front of him, because he is rotating at the same rate that the hammer is revolving around him. The thrower is obviously rotating, though. It is all just a matter of perspective.

 

(By the way, we appreciate good punctuation and capitalization here. It's easier to read, and makes you seem less like a crazy person.)

It is not only a matter of perspective.You clearly states that the hammer is revolving(not rotating).that is what I am trying to say.

[insane_alien]

spunnery, if the moon was not rotating then a day on its surface would last roughly one year(it vary due to the orbit around the earth.) since it does not last one year, we can deduce that it is rotating while it revolves round a common axis with the earth.

[swansont]

It is not only a matter of perspective.You clearly states that the hammer is revolving(not rotating).that is what I am trying to say.

 

You can revolve and rotate, you can revolve without rotating, and you can rotate without revolving. The terms have specific definitions, and using them, the moon rotates.

 

If you want to make up your own definitions, then you have to go off and play by yourself.

[spunnery]

You can revolve and rotate, you can revolve without rotating, and you can rotate without revolving. The terms have specific definitions, and using them, the moon rotates.

 

If you want to make up your own definitions, then you have to go off and play by yourself.

Sorry, If you feel that i am still sticking on to something i understood. If you are not fed up,please can you explain motion (can be a sketch or explanation) of a body which is revolving without rotating.

[Royston]

Sorry, If you feel that i am still sticking on to something i understood. If you are not fed up,please can you explain motion (can be a sketch or explanation) of a body which is revolving without rotating.

 

Well, stick a tennis ball on a stick and spin it round your head, the tennis ball is not rotating on it's axis, but it's clearly revolving round your body. Now take the tennis ball off, stick it on the floor and spin it...the tennis ball is now rotating, but it's not revolving around anything.

 

Sorry, if that came across as patronizing, but it's really that simple.

[spunnery]

Well, stick a tennis ball on a stick and spin it round your head, the tennis ball is not rotating on it's axis, but it's clearly revolving round your body. Now take the tennis ball off, stick it on the floor and spin it...the tennis ball is now rotating, but it's not revolving around anything.

 

Sorry, if that came across as patronizing, but it's really that simple.

Tell me please if tennis ball with stick is analogy to moons motion around earth?

[Royston]

Tell me please if tennis ball with stick is analogy to moon?

 

No, it's just illustrating the distinction between a roatating body, and a revolving body. I just used the 'attached to a stick' just make it clear the tennis ball was in a fixed position in relation to the stick. The moon is both revolving and rotating.

 

So if you held the stick and spun round, and focused on a point on the tennis ball, that point wouldn't change. However, if the tennis ball was rotating as well (say the stick had a small motor on the end, rotating the ball) then that point would clearly dissapear from your line of sight...so that would be more analogous to the motion of the moon round the earth, but an analogy only, and hardly an accurate description. Anyway, hope that helps.

[spunnery]

No, it's just illustrating the distinction between a roatating body, and a revolving body. I just used the 'attached to a stick' just make it clear the tennis ball was in a fixed position in relation to the stick. The moon is both revolving and rotating.

 

So if you held the stick and spun round, and focused on a point on the tennis ball, that point wouldn't change. However, if the tennis ball was rotating as well (say the stick had a small motor on the end, rotating the ball) then that point would clearly dissapear from your line of sight.

But in the case of moon the point is not disapearing(always you see the same face of moon -except libberations),which means there is no motor fixed at the end of the stick.