Why do we always see the same side of the moon?

Question

Is it a coincidence that the moon rotates on its axis exactly once each time it orbits the Earth? Or is there a law of physics at play which would cause the same to be true for all moons orbiting all planets?

Answer 1

The moon does rotate once for every revolution & that's why we only see one side of it. Coincidence? No. The moon locks into this 1-to-1 relationship because it's not perfectly round & the earth pulls one side stronger. This happens with many other moons and also the planet Mercury, but the relationship is not always 1-to-1. It could be 2-to-3 (2 rotations for every 3 revolutions), or some other low ratio. Many moons do not lock in at all.

Answer 2

The Moon makes one complete rotation for each orbit around the Earth. If the Moon did not rotate, we could see all sides of the Moon. In fact the Moon does rotate, and we see only one face of the Moon. Because the Moon makes one rotation in exactly the same time that it makes one orbit around the Earth, we only see one face of the Moon.
Prove it: Draw a circle representing the Earth. Draw a larger cirle around it to represent the orbit of the Moon. At North, East, South and West draw smaller circles representing the Moon on the second circle you drew.
At the right side of the diagram, draw an arrow pointing toward the "East" Moon-circle from a point at the edge of the paper. This line, if you allowed it to go all the way across the paper, would cross the center point of the first and second circles as well as the center point of the "East" Moon-circle. The arrow represents the light of the Sun as it shines on the Earth and the Moon.
On each of the Moon-circles, color the half of the Moon away from the Sun dark and leave the other half of each Moon lighter.
Now draw an "X" on the side of the four Moons facing the Earth. All four "X"'s should be inside the second circle.
The East Moon represents the New Moon as seen from Earth. We cannot see it since the sunlit side is facing away from Earth.
The North and South Moons are the quarter Moons, and the West Moon is the Full Moon. This demonstrates how the Moon does, in fact, rotate once per orbit around the Earth.
Earth's gravity holds the Moon in this orbit because it is so close to the Earth. In time, the Moon will eventually move away from Earth and perhaps will begin rotating faster.

Answer 3

Gravity has nothing to do with spin...gravity attracts objects at the center of mass and does not cause a torque...if one side of the moon was more attracted to the earth than the other you would see it wobble, which it does not do. The moon simpy has a period of rotation of 28 days and an orbit time of 28 days...big picture...God made it that way.

Answer 4

No. The earth rotates that's the reason of why time exists. do no longer you spot there are circumstances whilst the moon isn't seen (daylight hours). If somebody replace into on the moon, they might see the earth rotate and ought to in basic terms see the comparable spot in the international as quickly as each 24 (earth) hours.

Answer 5

because the moon orbits the earth not the other way round

Answer 6

Because it is in stable orbit, so always shows the same face to earth.

Answer 7

There must be a law of physics. These things don't happen by chance. God designed everything the way it is on purpose.

Answer 8

Well if you think about it, if id didn't rotate we would see different sides.

http://tech.groups.yahoo.com/group/NeatAstronomy/

Answer 9

it is a coinsidence and not reprisentative of all moon rotations.