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Author Topic: Why if the moon is rotating can we only ever see the same side?  (Read 9682 times)

Offline LeeE

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Why if the moon is rotating can we only ever see the same side?
« Reply #25 on: 11/02/2009 13:26:29 »
There's a difference between using the energy to speed you up, which would put you in an elliptical orbit, as SoulSurfer explained, or just using it to raise or lower your orbit; it comes down to the direction in which the energy is applied.  If you apply it in the direction of your orbit it will speed you up but put you in an elliptical orbit but if you apply it at right angles to your orbit, along the axis through your craft and the body you're orbiting, it'll just take you 'in' or 'out', which will have the consequence of speeding you up or slowing you down.  This is how spacecraft actually rendezvous in orbit; the craft that has to reach the orbiting target doesn't try to directly catch-up or slow down to reach each it, which would leave it in an elliptical orbit, but shift to higher or lower orbits to end up in (nearly) the same place at the same time.
 

Offline Vern

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Why if the moon is rotating can we only ever see the same side?
« Reply #26 on: 11/02/2009 17:10:31 »
This is good to know; I did learn something. Now I know why the Orbiter Simulator program that I play with requires the Orbiter to be in a lower orbit to catch up to the space station. I had noticed that before but somehow it didn't register that the higher orbit was actually slower. Soul Surfer's explanation was very illuminating. I must apologize to jj73 for not paying closer attention. I'll try to do better :) Thanks for not beating me up two much.
 

lyner

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Why if the moon is rotating can we only ever see the same side?
« Reply #27 on: 11/02/2009 17:46:56 »
When talking about orbits it's useful to be sure when you're talking about velocity and when you're talking about angular velocity. There can be a lot of confusion if you don't.
 

Offline randalf

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Why if the moon is rotating can we only ever see the same side?
« Reply #28 on: 14/02/2009 07:58:19 »
My God, I feel so thick ???...but what does our Sun do to this process and for that matter what effect do the other planet have as well? Surely our near neighbours will affect the Earth in some way too that will influence this process.

I sent this to Chris but I think it is relevent in this topic; isn't it a series of big coincidences that the Earth, Moon and Sun are so perfectly proportioned and the distances are perfect in proportion to their sizes to creat such fabulous lunar and solar eclipeses? Does this happen routinely in the universe or are we "special" (lol)?
 

Offline Chemistry4me

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Why if the moon is rotating can we only ever see the same side?
« Reply #29 on: 14/02/2009 08:00:39 »
We're VERY special! [^][^]
 

Offline LeeE

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Why if the moon is rotating can we only ever see the same side?
« Reply #30 on: 14/02/2009 21:26:26 »
I sent this to Chris but I think it is relevent in this topic; isn't it a series of big coincidences that the Earth, Moon and Sun are so perfectly proportioned and the distances are perfect in proportion to their sizes to creat such fabulous lunar and solar eclipeses? Does this happen routinely in the universe or are we "special" (lol)?

It was always thought to be extremely rare and, until a plausible mechanism for it occurring was only relatively recently found, was regarded as inexplicable; there are no other bodies in our solar system where the ratio between the sizes of the planets and any of their moons even start to approach the ratio between the sizes of Earth and our Moon.  However, as it has clearly happened once, it's likely to have happened again in other places and now that we seem to have a plausible mechanism for it occurring here, it's probably considered to be a little less unlikely than it used to be.
 

The Naked Scientists Forum

Why if the moon is rotating can we only ever see the same side?
« Reply #30 on: 14/02/2009 21:26:26 »

 

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