This seems strange in a solar system of rotating objects.
2006-08-02 08:29:23 · 15 answers · asked by christopherryan_lt 2 in Science & Mathematics ➔ Astronomy & Space
The Moon turns on it's axis exactly once for each orbit it makes around Earth. This is because it is tidally locked, which means that friction from the tides has slowly changed it's rotation rate over millions of years to cause it to be this way. The same force is slowing Earth's rotation, slowly making our day longer. This is also true of several other bodies in the solar system; it isn't just our Moon that does this.
2006-08-02 08:35:25 · answer #1 · answered by campbelp2002 7 · 0⤊ 0⤋
Yes, it has to do with gravity. No, it has nothing to do with "friction". Friction is when two objects are in intimate contact and rub against each other. Friction causes heat. It has nothing to do with friction.
Gravity is a force that acts between two objects. The moon is acting on the Earth and the Earth acts on the moon. The Earth's gravity was acting to slow the rotation of the moon until the moon rotates exactly once per revolution. That's called the lowest energy point. If the moon still rotated faster than once a revolution, then gravity would continue to slow the moon's rotational speed. The rotation cannot get any slower, because (oddly enough) that would require energy to be put BACK into the moons rotation to fight the effect of Earth's gravity.
The moon has exactly the same effect on the Earth. When the moon was first formed, Earth's day was about 10 hours long. Because of the moon, it has slowed to 24 hours/day. Given enough time (if the sun doesn't swallow us first), the Earth's day will likewise slow to once a month because of the Moon's effect on us.
2006-08-02 15:53:43 · answer #2 · answered by ZenPenguin 7 · 0⤊ 0⤋
Actually, beyond all the right answers that point out that gravity gradient keeps the moon locked due to accumulated tidal effet, I just want to point out your last comment: "This seems strange in a solar system of rotating objects". If you check the data on the solar system, you will see that most moons have sychronous rotation and orbit, and always face their planet the same way. The reason for that is this is a point of equilibrium. All moons tend to go towards that point, and once there, since this is the stable position, just wobble around from then on. And since moons had billions of years to get there, several of them reached that point already.
2006-08-02 15:51:33 · answer #3 · answered by Vincent G 7 · 0⤊ 0⤋
The moon maintains a synchronous orbit around the Earth. Which means that from the point of view of the surface of the Earth, the same hemisphere is always visible (Synchronous_rotation, 2006).
This happens because the tidal forces form a planet rotating around a star "locks" its satellite(s) in place (Tidal_locking, 2006).
The way I envision this is that while the Moon rotates around the earth it is fundamentally rotating around the sun. If you stretch a slinky into the shape of a circle, you get a weird corkscrew shape. Now, follow the length of the slinky as it travels from end to end. From the center of the circle the slinky seems to oscillate closer then further as it goes around the center. Now imagine a spinning quarter taking a shortcut straight through the center of the slinky. From the center of the circle you see a spinning orb go around you. The orbit of The moon is like the slinky, the orbit of th earth is like the quarter, and the sun is at the center. From the point of view of the Sun you see all sides of the Moon and Earth eventually. From the Earth you only see one side of the moon.
2006-08-02 16:44:09 · answer #4 · answered by shin 1 · 0⤊ 0⤋
" The great act of faith is when a man decides that he is not God . "
...what the hell is that?
God has nothing to do with why the Moon faces the Earth. And just because you have no idea about gravity gradients and orbital mechanics doesn't mean that God had a hand in it!
Sorry, off topic... but as a person of math and science I can't stand when people bring up God when there is an actual scientific answer...
And yes... it is due to gravity gradients caused by both Earth's and the Moon's imperfect shapes, and uneven mass distributions. It is much the same for many other planets and their Moons.
2006-08-02 16:28:22 · answer #5 · answered by AresIV 4 · 0⤊ 0⤋
This happened when about 7,947 people asked the same question on yahoo answers. The man in the moon was so shocked the he change the orbit so he could watch so much craziness below.
It has to do with gravity of the earth imparting friction on the spinning moon until the spin matched it's rotation.
2006-08-02 15:36:45 · answer #6 · answered by Anonymous · 0⤊ 0⤋
N.A.S.A. has some sattelites that are held in the same manner with a heavy piece on a boom that will hold that side always facing the earth, From this u could assume that the heavy side always points to the earth. the moon does rotate once every 28 days and by doing so one side always faces the earth.
2006-08-02 16:14:23 · answer #7 · answered by JOHNNIE B 7 · 0⤊ 0⤋
the moon does rotate, but the rotation matches its orbital speed. If it did not rotate then you could travel around the world to see all sides of the moon.
2006-08-02 15:36:05 · answer #8 · answered by MINDNOVA 2 · 0⤊ 0⤋
the moon does rotate on it's axis ... strangely enough, it's "day" and "year" are identical in length. as it moves around the earth, it is also rotating on it's axis, making it seem as though it does not rotate at all
2006-08-02 15:36:23 · answer #9 · answered by krux 1 · 0⤊ 0⤋
because the rotation period of moon on its axis is same as dat of earth's rotation period dat is y wen ever v c moon v always c d same side.
2006-08-02 15:36:14 · answer #10 · answered by ani 2 · 0⤊ 0⤋