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The Moon and The Tides

  1. Apr 9, 2005 #1
    Morning everyone!

    I was up late a few nights ago and I noticed how large the moon looked in the sky. Being a creature of habit myself, I began to wonder why the moon controls the ocean tides. I've been thinking about it and I couldn't come up with an answer. The moon controls the tides. Thats all I really know. I then began to wonder if the moon controls any other phenonmenon here on Earth. Does anyone have any thoughts?
     
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  3. Apr 9, 2005 #2

    matthyaouw

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    The moon is a large mass and exerts significant gravitational pull on the earth, which has noticable effect on the level of water in the earth's oceans. Try to get your hands on a basic geography textbook- it should give you an explanation of it.
    As for other earth phenomenon- for one, I'd speculate that the earth's atmosphere shows simlar 'tides' and this may have influence on winds and other weater. Whether this has been researvhed or not I'm not sure.
     
  4. Apr 9, 2005 #3
    Hmm, I wonder if I weigh less when the moon is above me and weigh more when the moon is on the opposite side of the Earth? I imagine that I would, but it must be an almost insignificant amount.

    Yeah, the moon exerts a gravitational force on the Earth. It raises the water level on one side of the planet and lowers it on the other. As the Earth rotates it creates the tides. The tides are hugely important to global weather systems. Weather patterns like El Nino are created by tidal forces and solar energy.

    What was the question again?
    Huck
     
  5. Apr 9, 2005 #4

    brewnog

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    This is incorrect.

    The water level is RAISED on BOTH sides of the globe, both nearest and furthest away from the moon.
     
  6. Apr 9, 2005 #5
    Brewnog is correct. I only accounted for the gravitational pull of the moon on the water of the Earth. I neglected to include the gravitational force of the moon on the Earth itself that pulls the Earth away from the water on the far side. Interesting, and it makes sense since there are 2 hightides and 2 low tides in one day.
     
  7. Apr 10, 2005 #6
    Huh, I didn't know it raised the water level on both sides of the planet at the same time.
     
  8. Apr 10, 2005 #7
    Matthyaouw, do you mean the moon might effect the jet stream as well as the tides?
     
  9. Apr 10, 2005 #8
    Huck, the orginal questions were; how does the moon affect the tides and does it affect any other natural phenomenon here on Earth? :smile:
     
  10. Apr 11, 2005 #9

    matthyaouw

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    I wasn't really thinking specifically jet streams... perhaps the height of the tropopause, much like it affects the height of the water. I suppose this could in turn affect winds and pressure, and thus the jet streams to some extent. I am merely speculating though, so I wouldn't give it too much thought. I might look into this more once my exams are over.
     
  11. Apr 11, 2005 #10

    brewnog

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    We've missed one.

    The Moon is well known to temporarily increase the global population of wolves for a few hours each lunar cycle...
     
  12. Apr 11, 2005 #11

    matthyaouw

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  13. Apr 11, 2005 #12

    DaveC426913

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    A better way to think of this is that is raises water on the near side of the planet, but "slacks off" on the other side.

    The water on the far side of the planet (with respect to the Moon) is under less pull, and more accurately "falls off" the bottom. To those of us standing there ("upsidedown" wrt Moon :) ) this is experienced as a raising of the local water level.
     
  14. Apr 14, 2005 #13

    Phobos

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  15. Apr 14, 2005 #14

    Ouabache

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    Also don't forget, all of us (bags of water) are affected by the moon's gravity.
    However some are affected moreso that others, they of course are lunatics. :surprised
    Something to ponder.. If we had no moon, would we (humanity) still be here? Would the earth's rate of spin change?
    Would the earth wobble to the same extent or wobble wildly out of control?
     
  16. Apr 15, 2005 #15

    Phobos

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    The tidal interaction between the Earth & Moon slows the Earth's orbit. A billion years ago, days were a few hours shorter. (I'm estimating...a quick Google would likely give you the exact rate)
     
  17. Apr 15, 2005 #16

    Ouabache

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    That is interesting.. I suppose that may have to do with the moon's recession away from earth. (estimated at 3.8cm/yr). That would make sense. As the moon recedes, it would have less gravitational influence on us and our rate of spin would decrease.
     
  18. Apr 16, 2005 #17

    matthyaouw

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    I just watched a nature documentary that said corals time the release of their eggs and sperm by the full moon.
     
  19. Apr 16, 2005 #18
    Sea turtles do the same thing, sometimes travelling thousands of miles.
     
  20. Apr 18, 2005 #19
    I heard about the coral reefs...had to especially after visiting the great barrier reef which is stellar at night even though I haven't seen it at night...all brown an crusty looking during the day time though. I knew a bit about the turtles too. It always amazes me how attuned to everything animals are.
     
  21. Dec 13, 2006 #20
    Weight gain/loss

    So, at average distance of the moon (~384400 km) and diameter of the Earth (~6400km), the acceleration due to the Moon's gravity on opposing sides of Earth is only different by ~10^-6 m/s^2. This, as compared to acceleration of gravity from Earth (~9.8 m/s^2) should translate to pretty insignificant weight gain/loss:wink:
     
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