Why does the moon always shows the same face to us ? What is the mecanics that explain it ?

Question

Also, I am under the impression that other moons of the solar system behave the same (I was reading an article about Saturn's moon Lapetus, and it seems that this moon also shows always the same face to its center planet).... is that true ?

Answer 1

http://www.digipro.com/Trials/moon.html

"The Moon is tidally locked to the Earth. When two rotating bodies orbit each other, they raise tides in each other. These tides cause mechanical friction. So tidal activity absorbs a lot of energy out of the rotational energy of the bodies. In other words, the energy in the form of rotational inertia is partially converted into tidal, geophysical changes in the bodies involved. The Moon's rotational inertia has been exhausted, converted into geophysical change in the Earth and Moon. The Moon, being much smaller than the Earth, long ago dissipated enough energy to lose rotation so that its tidal bulges are now always aligned with the gravitational pull of the Earth"

Answer 2

Man, some of these answers really make me want to tear some heads off. Everybody is saying we can't see the far side of the moon because it's rotational speed is equal to it's revolutional speed. I know what you're asking though, and you're wondering why those two speeds are equal. One of the "leading" theories is that tidal locking has caused it. The same gravitational forces that cause the tides slowed the moons rotation down until the heavier side of the moon was always facing us. I put "leading" in quotes because most "leading" theories these days are stupid, including this one. If gravitational forces caused this locking, then why does Venus always show the same side towards us when we pass close to it? The real reason why we are locked with Venus and the moon is electromagnetics. The same currents that cause the solar "wind" (a misleading term since it acts more like an electric current than wind) have locked the moon down with Earth. In order to understand it, you first have to realize that the Sun is not undergoing fusion in the core, like the "leading" theory states. Instead, the Sun is more like the filament in a light bulb and lights up when this huge current flowing through space passes over it. This is why the Sun rotates faster at the equator, and the solar wind accelerates away from it. This is also why sunspots reveal a cooler interior of the Sun, instead of something much hotter like the "leading" theory says it should be. These same currents also pass through the Earth and all the other planets, but since the majority of this flow is through the Sun everything spins around it. The energy flows from South to North, as you can see with the right thumb test. Your right thumb points up (the direction of the current) and your fingers curl in the direction the magnetic field spins. I don't know why scientists haven't discovered the electrical nature of the Universe yet. Everywhere we look in space we see the workings of magnetic fields and plasma filaments. We've observed double-helix galaxies as well, just like our DNA, so this should kind of tip us off to the big theory of everything scientists are looking for. *** Also, what the hell is this guy below me talking about? The rotation of the moon on its axis is equal to how long it takes it to revolve around the Earth. This is why it is always showing us the same side. What he wants to know is why the moon does this. ***

Answer 3

It's because the moon is so lopsided that after billions of years, it has stopped rotating with respect to the earth. It has a bulkier side that slowed down it's rotation and eventually settled down. As a result, it now always faces the earth.

Answer 4

I have my own theory that moons of this sort came from large bodies colliding with their mother planets. When the moons' mass separated from their mother planets, their rotations were matched and they just stayed that way. Just a theory, but I believe that's what explains it best.

Answer 5

It is not quite symmetrical, and the slightly heavier side is attracted by Earth's gravity more than the lighter side. Over time that caused its rotational and orbital periods to synchronize. That call this a "tidal lock".

Answer 6

The period of rotation of the moon is the same as its day, the correct term for this a gravitational lock.

Answer 7

yo bro.. the moon's rotation period is equal to the revolution period.. so u don't get to see the other side.. as in , by the time the other side gets here, it's revolved and it's back to the square 1..

Answer 8

Campbel? are you sure about this answer... Do you have any sources? I've not heard that one before. Given your history here, I'd give you the nod on the answer, but would like to read more material if available.