why do we see the same moon face?

Question

in laymans terms, why is it the moon always presents the same side to the earth.

Answer 1

Because its orbital period is about 28 days and it also rotates on its axis once every 28 days.

In fact, this is an approximation but it illustrates the point. Try it out by moving a coin around another. You can see that if it spins on its axis once for every revoultion about the planet then it will always present the same face to the planet.

Answer 2

The Earth is slowing down because of the Moon's gravity by tidal friction. The Earth is more than 80 times more massive, so a permanent "high tide" has formed on the Moon with a favorable orientation towards the Earth. Eventually (billions of years from now), the Earth will keep one face towards the Moon.

Answer 3

Without drawing a guide circle, cut a circle out of a piece of card. Stick a pin through the middle, hold the card circle vertically and spin it. It will slow to a stop, but because your circle is not perfect, the same half will always hang downwards thanks to gravity.

When formed, the moon was spinning freely, but it is not a uniform sphere, so over billions of years, it slowed to a stop and now hangs its heavy side towards Earth.

Because the moon has a secondary gravitational influence (Sun) and an elliptical orbit, it actually wobbles a little bit side to side and pole to pole, so from Earth, over time, you can see 58% of the moon's surface.

This state is called 'captured rotation', and many moons we know of are in this state, but not all.

Answer 4

This is quite common for things in close orbit. The combined gravity of earth and the moon tend to stop it rotating relative to the earth. The effect is quite useful with TV and GP satellites The same happens with the sun and Mercury.

Answer 5

The moon rotates on its axis at the same rate as it rotates about the Earth. About 2 pi radians per month.

Because the two rates are the same, we see the same view of the moon from Earth.

Two people who wanted to check this out could easily do so.

Let the observer stand in one place, perhaps in a gymnasium and watch the other walk around her in a circle. If the walker always kept her face toward the viewer as she walked, she would note that she looked, in sequence, at every position in the gymnasium, and only one time per cycle around.

To walk this way, she would have to walk like a crab on some parts of the cycle. If the walker just walked with her face always forward, the observer would see her from every direction.

Answer 6

it takes the same time for the moon to rotates on it axis as it does to orbit the earth, yeah it's a cosmic coincidence and here's another one; the moon is 400 times smaller than the sun but the sun is 400 times further than the moon from earth, thats why when we get a solar eclipse, the moon covers the sun almost exactly. satelites on other planets in the solar system don't behave this way. my answer to put simply is coincidental.

Answer 7

the moon rotates one full turn in the same time it takes to orbit the earth. This means that it always shows the same face to the earth.

Answer 8

'The Moon is in synchronous rotation, meaning that it keeps nearly the same face turned toward Earth at all times.' Wikipedia

Answer 9

The moon follows our orbit as we also follow the sun's orbit.
Think of a ball attached to your foot with a rod ,between the foot and the ball,(the rod is the bit between youre foot and the ball).this is the gravity.
It is the gravity that allows you to stay in youre place,it also allows the ball to turn wherever you turn,but the rod moves when you move,but the ball moves in the same direction.
The ball is gaught on youre rod ,but you cannot see the other side of that ball.

Answer 10

The Moon keeps the same face to us because it spins on it`s axis once for every orbit of the earth.