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Thread: Moon Rotation

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    Moon Rotation

    We know that we see only one side of moon... Moon is locked in synchronous rotation with the Earth, and always keeps one side toward us... What i cant get around or i dont know is... does the moon rotate around itself or is it stationary in that manner and just rotates around earth...?

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    Quote Originally Posted by rudra View Post
    We know that we see only one side of moon... Moon is locked in synchronous rotation with the Earth, and always keeps one side toward us... What i cant get around or i dont know is... does the moon rotate around itself or is it stationary in that manner and just rotates around earth...?
    Welcome to the message board, rudra.

    I'm not sure what you are asking. You seem to have answered your own question. In inertial space the Moon rotates on its axis during exactly the same period that it revolves around the Earth: 27.32 days. If you were to view the Moon from the Sun or another planet, you would see the Moon rotating on its axis. An astronaut remaining in one spot on the Moon would experience night and day, buy the entire process would take nearly a month.

    The situation is illustrated beautifully in another thread on this message board: http://www.bautforum.com/showthread....Moon-movements.!!!
    For astronomical graphics and data visit
    www.CurtRenz.com/astronomical

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    Quote Originally Posted by rudra View Post
    We know that we see only one side of moon... Moon is locked
    in synchronous rotation with the Earth, and always keeps one
    side toward us... What i cant get around or i dont know is...
    does the moon rotate around itself or is it stationary in that
    manner and just rotates around earth...?
    The Moon rotates. It doesn't add information to say it rotates
    "around something". You can tell it rotates because an observer
    sitting still on the surface would see the distant stars move
    across his field of view. And that is, of course, because the
    direction he is facing is constantly changing.

    However, there are two locations on the Moon's surface -- the
    rotational poles -- where all the stars appear to go around the
    zenith without rising or setting. An observer lying on his back
    at either of the poles would be facing in the same direction
    all the time. A star directly overhead would stay there. But
    the orientation of his body would still be constantly changing.

    You could reasonably say that the Moon rotates around the
    "axis" which is defined by the two poles. This is different in
    principle from something which rotates around an "axle", though
    there might not be any practical difference. An observer on a
    wheel rotating aound a fixed axle could see the same thing as
    an observer on a freely-rotating body like the Earth or Moon.

    In addition to rotating, the Moon revolves about the Earth,
    similar to how the Earth rotates and also revolves about the
    Sun. The Earth and the Moon are revolving about the Sun
    together, as a system.

    Although the Earth and the Moon have separate rotations,
    with completely different periods, they can be considered
    as a system to have a rotational period equal to the period
    of the Moon's revolution around the Earth. In this way,
    rotation and revolution can be difficult or impossible to
    distinguish from each other. The Milky Way galaxy, a
    collection of billions of stars, can be said to have a period
    of rotation of about 220 million years at the Sun's distance
    from the center. Each individual star in the galaxy has its
    own period of revolution around the galaxy's center.

    A person very distant from the Milky Way would not be able
    to see any individual stars, so would not be able to measure
    their periods of revolution, but they could see the rotation of
    the system of stars as a whole, and measure its period.

    Same thing for a hurricane. Each individual air molecule
    revolves around the hurricane's center, but it is only the
    rotation of the whole air mass that is observed.

    Please let me know if that helps or is confusing!

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

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