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Originally posted by gottago
The moon always shows the same face to us; it does not rotate on its axis, it rotates around the earth.
Originally posted by Springer
WeedWhacker, I would love to learn more about the "simulator bunk" as you put it. Seeing as how you are currently a pilot, you are very qualified to speak on the issue.
Maybe you could put together a solid post about how it's not only possible to crash planes into buildings in a simulator, but you've done it yourself. A video of you doing it would be stellar!
The moon rotates on its axis once every 29 1/2 days. That is the period from one sunrise to the next, as seen from the lunar surface, and so it is known as a lunar day. By contrast, Earth takes only 24 hours for one rotation.
The moon's axis of rotation, like that of Earth, is tilted. Astronomers measure axial tilt relative to a line perpendicular to the ecliptic plane, an imaginary surface through Earth's orbit around the sun. The tilt of Earth's axis is about 23.5 degrees from the perpendicular and accounts for the seasons on Earth. But the tilt of the moon's axis is only about 1.5 degrees, so the moon has no seasons.
Another result of the smallness of the moon's tilt is that certain large peaks near the poles are always in sunlight. In addition, the floors of some craters -- particularly near the south pole -- are always in shadow.
The moon completes one orbit of Earth with respect to the stars about every 27 1/3 days, a period known as a sidereal month. But the moon revolves around Earth once with respect to the sun in about 29 1/2 days, a period known as a synodic month. A sidereal month is slightly shorter than a synodic month because, as the moon revolves around Earth, Earth is revolving around the sun. The moon needs some extra time to "catch up" with Earth. If the moon started on its orbit from a spot between Earth and the sun, it would return to almost the same place in about 29 1/2 days.
A synodic month equals a lunar day. As a result, the moon shows the same hemisphere -- the near side -- to Earth at all times. The other hemisphere -- the far side -- is always turned away from Earth.
People sometimes mistakenly use the term dark side to refer to the far side. The moon does have a dark side -- it is the hemisphere that is turned away from the sun. The location of the dark side changes constantly, moving with the terminator, the dividing line between sunlight and dark.
The lunar orbit, like the orbit of Earth, is shaped like a slightly flattened circle. The distance between the center of Earth and the moon's center varies throughout each orbit. At perigee (PEHR uh jee), when the moon is closest to Earth, that distance is 225,740 miles (363,300 kilometers). At apogee (AP uh jee), the farthest position, the distance is 251,970 miles (405,500 kilometers). The moon's orbit is elliptical (oval-shaped).
The Earth’s moon rotates (spins on its axis), every 27.32166 Earth days. It revolves around the Earth in the exact same period - every 27.32166 Earth days. Because of the synchronization of revolutionary and rotational periods, the same portion of the moon’s surface is always directed toward the Earth.
Thanks for your question. The answer is actually 'Yes the moon does turn on
its own axis' and 'yes, we do see the same surface all the time.'
You see the moon turns on its axis at a rate that means that it turns once
every 29.5 days - it also takes 29.5 days to travel around the Earth. As a
result, we always see the same face of the moon.
If you have trouble visualising why this is true - pretend that you are the
moon. Find an object like a chair (you will pretend that the chair is the
Earth). Now move around the chair so that your body always faces the chair.
As you move around - you will have to turn your body so that it faces the
chair. You have to turn your body a full rotation every time you do a full
circuit of the chair.
I hope this helps you.
The Moon's orbital period is 27.322 days. Because of this motion, the Moon appears to move about 13° against the stars each day, or about half of a degree per hour. If you watch the Moon over the course of several hours one night, you will notice that its position among the stars will change by a few degrees. The changing position of the Moon with respect to the Sun leads to lunar phases.
Most inner moons of planets have synchronous rotation, so their synchronous orbits are, in practice, limited to their leading and trailing Lagrange points.
Originally posted by budski
We've all got to make a living - I think that JL stumbled upon a very good way to earn a living through CT's, and some of his stuff was truly rivetting.
Originally posted by weedwhacker
Doesn't anyone understand science? Or astrophysics!?!?!
Originally posted by Solarskye
Here's an example of a non-synchronous & synchronous moon orbit with the earth and sun.
It's very tricky and I still wonder how it does it so perfectly everytime.
Sorry I can't embedd but you can view it at youtube with my hyperlink.
[edit on 5/6/2008 by Solarskye]
Originally posted by seagull
All this arguing...Lear's gotta be lovin' it. On that note, I'm not gonna give him anymore satisfaction. Bye, all.