wetcw@pyuxa.UUCP (T C Wheeler) (06/13/84)
I am truely amazed by the answers to the moon question. Now, for once and all, there is a difference between orbiting and rotating. Suppose the moon were to stop dead in its track. Notwithstanding the effect of such an occurance, what would the moon do? It would NOT rotate. It would present the same face to the earth at all times. Rotating on an axis assumes that from a fixed point in space, the body presents different faces at different times. Imagine that the moon is is at half-moon stage. Imagine further that you can position yourself 1000 miles above the surface of the moon just at the point of night and day. Now, remain in this position for 28 days and observe. What happens? Nothing. Your position relative to the surface reamains the same as does your position in respect to the earth except, the earth goes through 28 revolutions while you are there. You are still 1000 miles above your predetermined spot. The light reaching the moon from the sun has moved over the surface of the moon due to the relationship of the sun to the moon's orbit, not because the moon is rotating. The moon's "day" is a result of its orbit, not its rotation. The question I must ask of the rotating moon people is "Where are the poles or ends of the moon's axis?" "Where is the moon's equator?" If the moon were to be "rotating", then there must be an axis for it to rotate upon. Since all maps and charts of the moon are arbitrary depictions based on nothing more than convention, who discovered the true axis? To sum up, the moon has NO tangential acceleration relative to its surface. It HAS tangential acceleration relative to its orbit. T.C. Wheeler
jso@edison.UUCP (06/15/84)
> Suppose the moon were to stop dead in > its track. Notwithstanding the effect of such an occurance, > what would the moon do? Huh? If there was no effect of the occurance, the moon wouldn't change much. You didn't say whether "stop dead in its track" referred to orbiting the earth or rotating about its axis. This statement is meaningless. > It would NOT rotate. It would present > the same face to the earth at all times. Rotating on an axis > assumes that from a fixed point in space, the body presents > different faces at different times. Talk about geo-centrism! The earth is a fixed point is space?!! What's so special about the earth? > ... Your position > relative to the surface reamains the same as does your position in > respect to the earth except, the earth goes through 28 > revolutions while you are there. You are still 1000 miles > above your predetermined spot. So? That just means that the moon keeps the same face to the earth at all times (close enough) - we know that already! > The question I must ask of the rotating moon people is > "Where are the poles or ends of the moon's axis?" > "Where is the moon's equator?" > If the moon were to be "rotating", then there must be > an axis for it to rotate upon. Since all maps and charts > of the moon are arbitrary depictions based on nothing > more than convention, who discovered the true axis? The axis is irrelevant to maps and charts! Stand on the equator and see the sun directly overhead. Go to the pole and watch the sun stay at the same distance above the horizon. (Oversimplifying, I know.) You can do the same thing on the moon. > To sum up, the moon has NO tangential acceleration relative > to its surface. It HAS tangential acceleration relative > to its orbit. You throw in buzzwords (the wrong ones) and then use them incorrectly. How about: <<The moon's surface has no tangential velocity relative to x. The moon's center of gravity has tangential velocity relative to x.>> Now, what is x? If x is the earth, fine, but again, why the earth - The earth-moon system is in such a tight relationship that this is meaningless. Picture yourself a million miles or so up from the earth's axis. (You do agree that it has one, right. :-) ) The earth is rotating: relative to the coordinate plane, a vector though the center of the earth and a point on the surface sweeps through all directions. Now picture a point on the moon's surface which always faces the earth. A vector through the moon's center and this point also sweeps through all directions. Therefore, the moon rotates. | Y+ | | o <- moon | X- -----------O <- earth --------X+ | | | | Y- John Owens ...!{ {duke mcnc}!ncsu!uvacs houxm brl-bmd scgvaxd }!edison!jso