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sundaju
2008-Oct-05, 04:01 PM
I understand that the moon does rotate about its axis once and also
during the same time, it revolves around the earth once.
Is there a specific reason to this or is it just a rare coincidence?
If it had not been doing so, what would have been the fate of earth
and the beings living in it?

Grashtel
2008-Oct-05, 04:12 PM
I understand that the moon does rotate about its axis once and also
during the same time, it revolves around the earth once.
Is there a specific reason to this or is it just a rare coincidence?
If it had not been doing so, what would have been the fate of earth
and the beings living in it?
The reason is that it is tidally locked (http://en.wikipedia.org/wiki/Tidal_locking), ie the tidal forces created by its interaction with Earth has slowed its rotation until its the same as its orbital period. Its a common situation lots of the closer in moons in the solar system are tidally locked and most of the extrasolar planets that have been found are very likely tidally locked as well.

cjameshuff
2008-Oct-05, 04:13 PM
I understand that the moon does rotate about its axis once and also
during the same time, it revolves around the earth once.
Is there a specific reason to this or is it just a rare coincidence?

Tidal drag...the side of the moon nearer Earth is pulled toward it more strongly than the farther side. When it was still rotating, this constantly stretched it and the moon's resistance to being stretched resulted in a drag on its rotation relative to Earth, so it slowly settled into its current situation with one side face always facing Earth.



If it had not been doing so, what would have been the fate of earth
and the beings living in it?

There would have been fewer misconceptions in ancient cultures about it being a flat object. That's about it. Whether the moon is rotating has no effect on Earth aside from the moon's appearance in the sky.

The same tidal drag effects converted some of the rotational energy of the Earth and moon into the moon's orbital energy, raising its orbit. If that hadn't happened yet, it would be closer, would appear larger in the sky, and tides would be higher. The increased tidal effects on Earth might increase earthquakes and volcanism.

sundaju
2008-Oct-06, 11:42 AM
Does the tidal effect add upto the gravitational pull exerted by earth over moon?

Where does the ocean get the energy from to create tidal waves?


At the expense of sounding ignorant, I have the following question.

I thought it was the pressure from the earth's inner layer that is thrust upon the ocean bed that gets released as tidal energy. But not sure about this... Are there other forces that create the volatility of the seas?

I also read that the moon's counter gravitational pull causes the tides.

PraedSt
2008-Oct-06, 12:39 PM
Mmmm...from your location, your questions, and the phrases you use in your post I think you may be confusing tides with tsunamis.

'Tidal wave' is a common term for 'tsunami', and it's completely misleading, wrong, and should not be used. Tsunamis have nothing to do with tides.

Also, hope you and your family were ok during the tsunami.

As for tides and tsunamis, start here, and see where that leads you:

1. Tides on Earth (caused by the gravity of the Moon)
http://en.wikipedia.org/wiki/Tide

2. Tsunamis (caused by anything that results in a rapid displacement of a large amount of ocean water- earthquakes, volcanos, rockslides, meteorites, etc)


And 'Are there other forces that create the volatility of the seas?'

Yes. Lots.
Wind, the rotation of the Earth, tides, tsunamis, temperature differences are some. There are more I'm sure.

Hope this helps.

sundaju
2008-Oct-06, 12:55 PM
Also, hope you and your family were ok during the tsunami

Really fortunate to be alive still... I cannot forget that day when nature showed us who is the boss and why...


BTW, thank you very much for the explanation and the link... I have some food for thought...

PraedSt
2008-Oct-06, 01:04 PM
2. Tsunamis (caused by anything that results in a rapid displacement of a large amount of ocean water- earthquakes, volcanos, rockslides, meteorites, etc)

Sorry, forgot the link!
http://en.wikipedia.org/wiki/Tsunamis