2007-03-19 22:17:53 · 27 answers · asked by Senthil 1 in Science & Mathematics ➔ Astronomy & Space
The moon is currently "spin orbit coupled" (also called spin orbital resonance) with the earth.
what this means is that for every revolution around the earth, the moon also makes one full revolution. Because of this spin orbit coupling, one side of the moon always faces the earth.
So because of this spin orbit coupling, one side of the moon always faces the earth.
Mercury is spin orbit coupled with the sun. (for every 2 mercury days, 3 mercury years pass.) And several of jupiters moons are spin orbit coupled to jupiter.
We always see the same side of the Moon, so the Moon must rotate around its axis in the same time that it takes for the Moon to orbit once around the Earth. This is called a 1:1 spin-orbit resonance.
It takes on average exactly the same amount of time for the Moon to rotate once around its axis as it takes for the Moon to orbit once around the Earth (and in the same direction), namely 27 days 7 hours 43 minutes. For example, when the Moon has completed one quarter of its orbit around the Earth, then it has also rotated by 90 degrees around its axis (compared to the stars), so that we still look at the same side of the Moon.
This website explains it pretty well
http://www.astro.uu.nl/~strous/AA/en/antwoorden/maan.html#v476
Someone above said it is a geosynchronous orbit... that is wrong. Geosynchronous orbits are when something is locked in one place in the sky above a planet. It would be above exactly one spot on earth, and you would not be able to see it in distant locations. The moons orbit around the earth takes it across almost every nation on earth during its rotation. So for example if it was geosynchronous orbit above the USA, no one on the other side of the planet would be able to see the moon. EVER.
You also have 3 people who have said this"Because the moon doesn't spin on it's axis like the earth does. So what that means is we only see one side of it" I'm not sure what they mean, but the moon does have an axis, and it does have a rotational period and it does spin. They are also wrong. The moon is spinning at the same rate it travels around the earth. If it was not spinning we would definately see all of the moon from the earth.
2007-03-19 23:40:55 · answer #1 · answered by Adorabilly 5 · 1⤊ 0⤋
THE TIME BY THE MOON FOR THE ROTATION AND REVOLUTION IS THE SAME .
So when it completes 1 rotation and 1 revolution its that time when WE see the moon. So we feel that the moon does not rotate around its axis. But it does. So basically the main reason why we see only one side of the moon is because of this reason.
If you are willing to see the other side, go into space!
2007-03-20 05:49:48 · answer #2 · answered by Shivani P 2 · 2⤊ 0⤋
It is due to a phenomenon of astronomy called tidal locking.
In this case two orbiting bodies show only their face (and not back, or visa verse if they had a quarrel between them.. ha ha, any ways) to each other. It is not necessary that both of them should face each other, only either of the two can also keep on looking at the other. Here moon is tidally locked to the earth and keeps on looking towards earth. Another example can be geosynchronous satellite, in which the earth and the sat elite are tidally bound to each other and hence keep on looking towards each other.
this locking is not like any bound, but it is just a consequence of the fact that sometimes the rotational and revolutional periods are same.
here we should consider a strange fact that, if the moon were to be at the same distance as that of the geosynchronous satellite, then earth and moon would have got tidally locked to each other.
2007-03-20 09:19:28 · answer #3 · answered by girish k 2 · 1⤊ 0⤋
Because it's on the other side of the moon....and because the moon rotates at the same rate it revolves around the earth.
2007-03-20 11:13:14 · answer #4 · answered by xooxcable 5 · 0⤊ 0⤋
I wondered about that also.So on my own I thought about how can that be? Then it suddenly came to me.For each revolution(the complete distance the moon travels in 28 days) the moon makes 1 rotation on its axis(an axis is an imaginary line which passes through the center of the equatorial plane of the moon.There is a planet that does the same thing.It is the planet Mercury
2007-03-20 06:00:12 · answer #5 · answered by silverback7m 2 · 1⤊ 0⤋
We can't see the other side of moon because Earth & moon both completes one revolution in same time period.
2007-03-20 09:29:04 · answer #6 · answered by ankiani 2 · 0⤊ 0⤋
The moon keeps one side towards the earth all the time, the theory is that the moon and earth were once a single body, and as it tore in two, the two bodies kept the same rate of rotation.
to see the other side of the moon you have to go to that other side.
2007-03-20 05:26:07 · answer #7 · answered by Anonymous · 1⤊ 2⤋
While the moon is going round the earth it continually turns around a bit so that its back is always facing away from the earth.
2007-03-20 05:23:34 · answer #8 · answered by Anonymous · 1⤊ 0⤋
Because we are on one side of the moon.
2007-03-20 05:46:17 · answer #9 · answered by Nathan L 1 · 0⤊ 2⤋
as the earth rotaes the moon also revolves around the earth...therefore we only see one side of the moon
2007-03-20 09:36:08 · answer #10 · answered by nikaramirez30 2 · 0⤊ 0⤋