Something funny about the moon

I need some help from those of you out there that have a good understanding of our solar system. Can someone explain to me why the same side of the moon shows itself to us each day and night? I find it so strange that it always shows the same face when both the earth and the moon are revolving. You'd think it there would be some variance, but the same side always shows itself to us. Does it change somewhat over 1000's of years? For me its just so hard to believe that both the earth and the moon could keep it so exact for so long a time. Can anyone help explain this, perhaps in layman terms so it is easier to understand? Thanks all.

I wasn't sure myself, so I looked it up:

This otherwise bizarre phenomenon can be explained in terms of a subtle effect generated by gravitation and friction — tidal locking. Through their mutual gravitational attraction, the Earth and the moon create tidal bulges on each other. One bulge faces in the direction of the other body, and one faces away. These bulges generate heat through the friction of rock rubbing against itself. Over time, they siphon energy away from the rotational momentum of both bodies, producing a breaking effect.

Because the Earth's mass dominates the Earth-Moon system, the moon experiences the greater braking effect. Over time, the moon's rotation has progressively slowed until the rate of rotation matches the rate at which the tidal bulge moves around the body

www.wisegeek.com...

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[edit on Fri Jan 9 2009 by Jbird]

reply to post by Alienmojo


It's not that simple to explain but it is because of a process called tidal locking. It is not unique to our Moon, most of the larger moons of all the other planets are also tidally locked, showing only one face to their planet.
en.wikipedia.org...

This little video explains it in a way even I can understand.

Originally posted by nyarlathotep
I wasn't sure myself, so I looked it up:

This otherwise bizarre phenomenon can be explained in terms of a subtle effect generated by gravitation and friction — tidal locking. Through their mutual gravitational attraction, the Earth and the moon create tidal bulges on each other. One bulge faces in the direction of the other body, and one faces away. These bulges generate heat through the friction of rock rubbing against itself. Over time, they siphon energy away from the rotational momentum of both bodies, producing a breaking effect.

Because the Earth's mass dominates the Earth-Moon system, the moon experiences the greater braking effect. Over time, the moon's rotation has progressively slowed until the rate of rotation matches the rate at which the tidal bulge moves around the body

www.wisegeek.com...

 

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[edit on Fri Jan 9 2009 by Jbird]

Thanks nyarlathotep! I've looked it up myself before and have a basic understanding of it... but I just can't seem to understand it enough. I just can't get it to compute in my mind's eye when I envision the earth and the moon... then again I have trouble understanding why its not bright ALL the time. I do appreciate the effort though...thanks again.

Originally posted by Phage
reply to post by Alienmojo

 

It's not that simple to explain but it is because of a process called tidal locking. It is not unique to our Moon, most of the larger moons of all the other planets are also tidally locked, showing only one face to their planet.
en.wikipedia.org...

Hey Phage! That does make sense and I'm surprised that I never thought of looking into that before! I get the basics of it and all... but its still hard to see in my mind. Thanks for the help brother.

ps...just for you Phage.. "Evil! Pure and simple! Straight from the eighth dimension!!!!" God, I love that movie.

[edit on 9-1-2009 by Alienmojo]

Originally posted by ziggystar60
This little video explains it in a way even I can understand.

AWESOME...totally awesome ziggy. Now I get it!!! I just couldn't get the picture right in my head... but that video really explained it well. Thanks so much for helping me out guys...

The moon has both an amazing orbit and spin. The orbit perfectly aligns with our day/night cycle and allows eclipses (which are also due to the moon being a perfect distance from us). The spin is such that the same side is always facing us.

The odds of that happening are unthinkably large. Draw what conclusions you will.

Originally posted by avingard
The moon has both an amazing orbit and spin. The orbit perfectly aligns with our day/night cycle

Not so sure about that, the orbit is slow but it's not sun-synchronous, which is why the moon can be seen both during the day and at night at different times in its orbit, which brings us to...

and allows eclipses (which are also due to the moon being a perfect distance from us).

On that I agree, the distance and size are amazingly perfect.

The spin is such that the same side is always facing us.

The odds of that happening are unthinkably large. Draw what conclusions you will.

Thanks to lunar libration we can actually see a bit more than just the same side, almost 60% of the surface (though some of it can only be seen from an extreme edge-on view). Tidal locking isn't unusual though, it's pretty standard among moons. In fact, it's inevitable given enough time and gravity. The earth would eventually tidally lock to the moon if the solar system lasted long enough (it won't) and pluto and charon are tidally locked to each other.