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Has the Moon always had same orbit? *Question*

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posted on Feb, 25 2011 @ 03:23 PM
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You can ZOOM IN on the MOON here. I got this link from another thread.

The question I have is that if the Moon only reveal one side of its surface from Earth, shouldn't there be a bald spot somewhere on the moon surface free from meteor craters? My point is that there should be a smooth part where the path of earth blocks the moon from open space.

I have scanned through the entire surface and when you zoom in there is hardly an inch not peppered with craters. I guess I am wondering if this is proof that the Moon was put in orbit rather than evolved over time from one of two two accepted theories on how the moon was created.

Obviously, I may be ignoring a simple detail that explains this easily. However, I can't muster one myself. So can the kind members of ATS explain why there isn't a bald spot of craters on the moon from the shadow of the Earth?

If my brain calculates correctly, it should be a line of smooth surface across the Moon from where the moon obits the planet.


The Moon is in synchronous rotation, meaning that it keeps the same face turned toward the Earth at all times. This synchronous rotation is only true on average, because the Moon's orbit has a definite eccentricity. As a result, the angular velocity of the Moon varies as it moves around the Earth, and is hence not always equal to the Moon's rotational velocity. When the Moon is at its perigee, its rotation is slower than its orbital motion, and this allows us to see up to eight degrees of longitude of its eastern (right) far side. Conversely, when the Moon reaches its apogee, its rotation is faster than its orbital motion and this reveals eight degrees of longitude of its western (left) far side. This is referred to as longitudinal libration.


Source


Thanks Again,

AAC
edit on 25-2-2011 by AnAbsoluteCreation because: (no reason given)




posted on Feb, 25 2011 @ 03:33 PM
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Well a quick wiki scan came up with this

Tidal forces between Earth and the Moon have slowed the moon's rotation so that the same side is always facing the Earth. The other face, which is never visible from the Earth in its entirety (18% of it can be seen under some conditions), is therefore called the "far side of the Moon"

Which implies that indeed there was a time (far in the past) when the moons orbit was not synchronous.

I will dig a bit more
Far side of the moon

Edit to add
Heres a more detailed explanation link
edit on 25-2-2011 by davespanners because: (no reason given)



posted on Feb, 25 2011 @ 03:47 PM
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reply to post by AnAbsoluteCreation
 


It's been confirmed since Apollo (via the retro-reflectors placed on the surface by Astronauts) that the Moon's orbit is spiralling away....rate of a few centimeters every year. Inferring that in reverse, then it's logical and reasonable that it WAS much closer, in the long ago past. This fits with the current (and dominant) theory of its creation.

AS TO the near side, versus far....and meteor vulnerability, I like this site, and GIF for illustration (AND, it also has a secondary educational value, RE: light speed):

Earth-Moon scale


The relative sizes there are to scale....as is the distance. As you can see, the Earth doesn't act as much of a "blocker", even for the hemisphere of the Moon facing our direction.

One aspect, though, is the potential for the Earth's gravity well to "overwhelm" an inbound object, and deflect it from course....but, that can be double-edged, as well, if you think about it. An object that otherwise might have missed the Moon entirely, might be 'attracted' toward Earth, because of its gravity, and thus impact the Moon.

One more thing: The near side is relatively less cratered because of the ancient molten flows onto the surface....this obliterated many early craters. Two more things..
....the majority of the major cratering event occurred LONG time ago....in the first billion or so years, after the Moon cooled from its molten state at formation.


edit on 25 February 2011 by weedwhacker because: (no reason given)



posted on Feb, 25 2011 @ 03:51 PM
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Thanks for those replies. Very helpful indeed.


AAC



posted on Feb, 25 2011 @ 03:56 PM
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reply to post by weedwhacker
 


I love the little graphic you linked to weed, that wasn't the scale that I had in my mind at all thought the moon would appear much nearer then that



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