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How to measure the rotation period of the moon?

  1. Jan 26, 2009 #1
    anyone know how scientists measure the rotation period of the moon?
    thank you!
     
  2. jcsd
  3. Jan 26, 2009 #2

    mgb_phys

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    Do you mean it's own rotation (ie a lunar day) or it's rotation around the Earth (a lunar month)
     
  4. Jan 26, 2009 #3
    its own rotation (lunar day)
     
  5. Jan 26, 2009 #4
    im trying to find articles/sources on it..but haven't found any yet
     
  6. Jan 26, 2009 #5

    mgb_phys

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    The moons day is the same length as the lunar month (27 days 7 hours 43.2min) - that's why it always points the same face toward earth.
    This isn't a coincidence, an effect called tidal friction means that gradually the Earth has slowed down the moon's rotation until it is now locked to Earth.
    It does rotate a small amount because of small variation in the orbit, you can see this from small changes in the shadows on craters.
     
  7. Jan 26, 2009 #6
    thanks!
    but are there any methods to calculate/measure it?
     
  8. Jan 26, 2009 #7

    mgb_phys

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    Well the lunar month you just record the time that the edge of the moon crosses some distance bright star and then note the next time it crosses it 28days later.
    For the day rotation you could measure the angle to the edge of some crater compared to the edge of the moon.
     
  9. Jan 26, 2009 #8
    oh okok..
    thanks alot!!
     
  10. Jan 26, 2009 #9
    do u know where i can find info on this??
     
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