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Why do the Earth and the Moon Spin Synchronously?

03/10/2007 12:33 AM

I am always puzzled why Earth and Moon Spin in Synchronous Manner. I feel that from present theories of formation of Planets and moons it is impossible to achieve such synchronization. There is some missing string in our current theories of planet formation and Gravitational force.

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#1

Re: Synchronization of Earth & Moon spin

03/10/2007 8:01 AM

Why?

Anyway, what do you mean they spin in a synchronous manner??

Some planets in the solar system spin the opposite direction...

As for the plane the planets are nearly aligned on, that can be explained by the dust cloud revolving around the sun as the planets 'condensed' out of it...

John.

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#2

Re: Synchronization of Earth & Moon spin

03/10/2007 5:21 PM

Well it seems to me that the earth and the moon spin in sync because it has to to sustain life.lol!

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#3
In reply to #1

Re: Synchronization of Earth & Moon spin

03/10/2007 9:31 PM

I mean Earth spins arout her axis in 24 hours, sameway does moon. Time is so synchronous, which puzzles me.

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#4

Re: Synchronization of Earth & Moon spin

03/10/2007 11:48 PM

Nandan,

There is nothing "missing" about the reasons for the rotation of the moon having become synchronized with its revolution about the earth (actually the earth and moon revolve about each other, around the center of mass of the earth/moon system).

This occurred over time as a result of the tidal forces produced in the moon by the earth, and it is both well understood and explained by current gravitational theory.

As for the formation of the moon, it most likely was "blasted" out of the earth as a result of a foreign body colliding with the earth, collisions being quite frequent in the early stages of our solar system.

Regards, Greg

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#5
In reply to #3

Re: Synchronization of Earth & Moon spin

03/10/2007 11:51 PM

tidal forces slowed and stopped the moon so it presents the same face to the earth

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#6
In reply to #3

Re: Synchronization of Earth & Moon spin

03/10/2007 11:55 PM

Nadan,

"I mean Earth spins arout her axis in 24 hours, sameway does moon. Time is so synchronous, which puzzles me."

WHOA!

The moon doesn't spin about her axis in 24 hours!

The moon doesn't revolve around the earth in 24 hours!

You are babbling utter nonsense, no wonder you are confused.

NO Regards, Greg

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#7

Re: Synchronization of Earth & Moon spin

03/11/2007 4:27 AM

FAR SIDE OF MOON IS HEAVIER. THATS WHY.

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#8

Re: Synchronization of Earth & Moon spin

03/11/2007 10:28 AM

The tidal force of the earth on the moon has sychronized its rotation on its axis to the revolution around the earth. If the moon rotated with respect to the earth, the friction caused by the tidal bulge over time would stop the rotation.

The real puzzle is the rotation of the planet Venus. It rotates in a retrograde manner and the period of rotation is such that it always presents the same side to the earth at the closest approach (synodic period). Tidal force falls off as the cube of the distance and has got to be neglibile at that distance.

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#9
In reply to #6

Re: Synchronization of Earth & Moon spin

03/11/2007 12:29 PM

Moon revoves around Earth in 30 days as well as spins about her axis in 30 days. Is it correct. I agree about my confusion. Do you think I am still confused.

Nandan

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#10
In reply to #3

Re: Synchronization of Earth & Moon spin

03/11/2007 2:21 PM

You said "I mean Earth spins arout her axis in 24 hours, sameway does moon."

Sorry but the moon only rotates once in about 28 days not once every twenty four hours!

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#11
In reply to #4

Re: Synchronization of Earth & Moon spin

03/11/2007 7:42 PM

I once heard that the Moon is progressively getting further from the Earth. Has anyone else heard this? What are the implications? How close did it start?

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#12
In reply to #7

Re: Synchronization of Earth & Moon spin

03/11/2007 8:24 PM

The reason that the one side of the moon always faces the earth is the heavy side has a higher gravitational pull. The near side of the Moon is quite literally heavier than the far side! That's because the near side had a thinner crust when the Moon was young, and lava flowed through the crust making big pools of dark rock called 'maria'. These are the markings that we see as the Man in the Moon.

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#13
In reply to #8

Re: Synchronization of Earth & Moon spin

03/11/2007 9:07 PM
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#14
In reply to #11

Re: Synchronization of Earth & Moon spin

03/12/2007 4:48 AM

About 20mm per day, according to local reports.

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#15
In reply to #12

Re: Synchronization of Earth & Moon spin

03/12/2007 5:27 AM

The near side of the moon has fewer craters than the dark side.Is this because the earth acts as a shield ? If so, can anyone establish the frequency of meteors etc blocked by the earth. I'm slightly worried about an ' extinction level event' , especially since my house is not very strong..If I see anything coming I'll post a warning , but it may be a bit hurried.

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#16

Re: Why do the Earth and the Moon Spin Synchronously?

03/12/2007 5:41 AM

Rotational speeds?

The earth do not rotates round its axis in 24 hours not even an average of 24h.

The earth actually makes an extra revolution in a year making the rotation relative to the "fixed" star background ±4 min shorter.

I thought the moon rotates around the earth in 29.5 days making moon months 29 and 30 days and the standard moon year 354 days.

To prevent summer from falling in winter an extra month was added every ±3 years.

Complicated but it worked. A specific dates coincides ± every ±19 years.

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#17
In reply to #13

Re: Synchronization of Earth & Moon spin

03/12/2007 8:37 AM

Great site! Now in my favorites! Has to be the clearest description of Tidal drag I've ever heard.

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#18
In reply to #16

Re: Why do the Earth and the Moon Spin Synchronously?

03/12/2007 1:43 PM

The moon travels around the earth in 27 days, 7 hours, and 43 seconds.

The word month is derived from the Old English word for moon. A month was originally the time between two new moons. Today astronomers refer to this period of time as a lunar month. Its average length is 29 days, 12 hours, 44 minutes, and 2.8 seconds, or 29.530589 days. The moon travels around the Earth in 27 days, 7 hours, 43 minutes, and 11.5 seconds. This is the sidereal month. The length is different to the lunar month because the earth is moving along its orbit around the sun. Calendar months usually differ in length, and all except February are longer than 29 days in order to accommodate the solar year, which is almost 11 days longer than a lunar year.

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#19
In reply to #6

Re: Synchronization of Earth & Moon spin

03/12/2007 5:15 PM

Greg,

I think you do not belong on this forum. You have no patience for those who are not as articulate as you. Surely the man meant that for every orbit around the earth the moon rotates on it's axis once. I too find it curious that the moon spins exactly once per orbit around the earth thereby presenting one face to the spectators here on earth.

You have responded this way to many posts on this forum including some of mine. I find that your responses do not add any value to the conversation. Why don't you just take a hike!!

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#20
In reply to #19

Re: Synchronization of Earth & Moon spin

03/12/2007 9:28 PM

To he who chooses not to reveal his name,

It is not a question of being articulate. It is a question of being flat wrong.

This is a "scientific/engineering" forum and as such we hew to science and physics as we understand them. Well intentioned people spend time here attempting to answer questions and help the questioners. Given that effort, there is (I feel) at least some responsibility on the part of questioners to attempt to answer their questions or inform themselves to the minimum extent that will at least enable them to understand the answers.

I made a courteous reply in post #4 where I attempted to address the OP.

If you choose to believe that the following is simply a post from someone who "is not as articulate as" me that is certainly your prerogative.

"I mean Earth spins arout her axis in 24 hours, sameway does moon. Time is so synchronous, which puzzles me."

You say:

"Surely the man meant that for every orbit around the earth the moon rotates on it's axis once."

Perhaps, but in two posts he said anything but that.

I have spent a lot of time here, most of it in trying to be helpful to the extent I am able. How much time have you spent and help have you offered?

As to your worthwhile suggestion that I should exercise more, perhaps by hiking, it is much appreciated.

Greg

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#21
In reply to #19

Re: Synchronization of Earth & Moon spin

03/13/2007 8:47 AM

Dear Guest,

The last paragraph in your response to Greg G. is inappropriate.

"You have responded this way to many posts on this forum including some of mine. I find that your responses do not add any value to the conversation. Why don't you just take a hike!!"

I'm sorry to have to discipline you publicly, but had you taken the time to register with CR4, I could have sent you a private message.

You've come to this forum asking for assistance. Good people are trying to help you. Everyone who has something constructive to say - including people that you don't like - has a right to be here. If you have a problem with an individual user, bring it to the attention of CR4 Administrators like myself.

Please read the site policy and register with CR4 before you post again.

Moose

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#22
In reply to #11

Re: Synchronization of Earth & Moon spin

03/13/2007 11:35 AM

My understanding is that it is because of the conservation of angular momentum. As the moon's tides slow the rotation of the earth, the angular momentum has to go somewhere, and it jacks the moon up into a slightly higher orbit.

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#23
In reply to #18

Re: Why do the Earth and the Moon Spin Synchronously?

03/14/2007 2:13 AM

Thanks for the correction.

I am loosing the paper war and cannot find my notes.

It is interesting to note that the moon calender actually provide for the correct number of days by introducing additional months in specific years.

the number of days is exactly the same if taken over a period of 17 - 19 years.

(Ignoring the century refinement)

It is further interesting to note that Bible prophecy's are based on 30 day months and 360 day years.

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#24

Re: Why do the Earth and the Moon Spin Synchronously?

03/14/2007 1:34 PM

Since we are on the subject of the moon... does the moon follow an equatorial orbit? or is it off-equatorial by x number of degrees... or is it in the same plane as the rest of the solar system... or is it none of the above?

Just kinda curious

Bill

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#25
In reply to #21

Re: Synchronization of Earth & Moon spin

03/15/2007 1:04 PM

Moose,

I am not trying to disrespect Greg. All I am trying to do is point out that the man is rude and if he deems the question baseless or "silly" then perhaps he ought not post a response, instead of insulting the poster. Greg is the one who's comments are inappropriate!

Regards,

-g

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#26
In reply to #25

Re: Synchronization of Earth & Moon spin

03/15/2007 3:23 PM

To Guest (from Greg G):

I'm sorry that you misunderstand my passion and strident way of responding to technical points in posts, as being rude, personal attacks, but it is those technical points that I directly address, not the personalities behind them. That you choose to continue to attack the messenger (in this case me), rather than ever addressing any technical disagreements on their merits or lack thereof, is unfortunate because this is a scientific/technical forum.

As such, when any of us post something here, that post becomes fair game for praise, refutation, or even ridicule based on its relevant technical content. Incorrect, misguided or illogical posts by anyone (certainly including myself) left uncorrected only sows misinformation and not only doesn't elevate the discussion but rather corrupts it and robs it of educational value. I come here in large part to learn from others as do most members.

You seem to be confusing the difference between technical aspects of a post being termed baseless, "silly", or "WRONG!", and a rude personal insult.

My suggestion would be to become a member and join the fray of the many subjects discussed/debated here on various technical points, and not get caught up on what you perceive to be personal insults.

Greg

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#27
In reply to #19

Re: Synchronization of Earth & Moon spin

03/15/2007 3:28 PM

Greg managed to "bite" my head off several times, but it was a pleasure!

You cannot demote someone for being articulate. This is a free forum, where exchange of ideas is the language, each participant with his typical manner. Why not except each other as we really are, inquisitive buggers! Long live the debate.

To the point: the apparent way in which the moon rotates around the earth, can suggest that the moon was once a chunk of earth's mass, probably detached momentarily to a higher orbit, then descended to it's currently apparent orbit.

This can be confirmed if accurate measurement is made to a decreasing shift in it's trajectory is made to be simulated in reverse

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#28
In reply to #20

Re: Synchronization of Earth & Moon spin

03/16/2007 5:25 AM

Greg , I side with you in these exchanges , but where has your "#4 " gone ? Kris

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#29
In reply to #28

Re: Synchronization of Earth & Moon spin

03/16/2007 6:01 AM

This is a forums classic. Some posts simply evaporate out-of-count. Maybe it was nit-picked by the admins.

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#30
In reply to #26

Re: Synchronization of Earth & Moon spin

03/16/2007 7:15 AM

Dear Greg,

I am really sorry for creating so much problem due to my confusion. I hope you will keep up your efforts to increase the knowledge of community on this site.

Nandan

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#31
In reply to #30

Re: Synchronization of Earth & Moon spin

03/16/2007 7:42 AM

Nandan,

Thank you for apologizing and helping to defuse the situation. I'm pleased that you've registered with the site. Welcome to CR4!

Best,

Moose

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#32
In reply to #28

Re: Synchronization of Earth & Moon spin

03/16/2007 11:57 AM

Kris,

Thank you.

My Post #4 is way down because I posted it to the original OP, rather than as a reply to a subsequent post. CR4 has settings that you can set to view the posts in numerical order, or indented as per who they were replying to.

If you scroll down and read the numbers you will find it.

It didn't evaporate, and wasn't removed, it is just the way CR4 orders posts in the indented viewing mode.

Regards, Greg

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#33
In reply to #32

Re: Synchronization of Earth & Moon spin

03/16/2007 12:20 PM

Thanks - Your quote about learning says it all ! Kris

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#34
In reply to #30

Re: Synchronization of Earth & Moon spin

03/16/2007 12:49 PM

Nandan,

Thank you for your comments. You owed no apology whatsoever to me though.

It was a "Guest" posting that took so much offense on a personal level to my post #6, but his opinions on my posts long predated this thread, and had nothing to do with you here, only me.

The only suggestion I would offer, and this is in general, not directed specifically to you, is that a questioner should make some effort to research/explore the topic of their question before posting in order to offer both a better, more detailed question, and be able to more fully understand the answers/comments offered by others. We all share an obligation to make this site as technically useful as possible, since it is we who will benefit.

I responded to your confused post based only on the words of the confused post as it read. I never implied you did anything wrong intentionally, and this certainly had nothing to do with you on a personal level. We all are victims of confusion at times.

As for myself, while I certainly ramble on at times, when responding to scientific/technical points I use a very strident, blunt style. The reasons are that many people read these posts, and do so quickly, rarely reading every post in a thread, or even every word in a post. By being as direct and clear on my points as possible I feel it makes it easier to read and easier to respond to if one disagrees with me. If I am wrong, and I have been, due to misunderstanding, confusion or ignorance, I want to draw someone out to tell me specifically how and where so that I can learn more.

The debate here is one of ideas, and scientific/technical issues, not personalities.

Regards, Greg

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#35
In reply to #24

Re: Why do the Earth and the Moon Spin Synchronously?

03/16/2007 2:30 PM

Bill,

"Unlike most satellites of other planets, the Moon orbits near the ecliptic and not the Earth's equatorial plane."

For a great link that addresses all these issues:

http://en.wikipedia.org/wiki/Moon#Orbit_and_relationship_to_Earth

Regards, Greg

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#36
In reply to #35

Re: Why do the Earth and the Moon Spin Synchronously?

03/16/2007 4:50 PM

Greg...

Much thanks for the information. I will try out your links. You never can tell... I might just learn something.

Bill

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#37
In reply to #31

Re: Synchronization of Earth & Moon spin

03/16/2007 11:39 PM

I feel that mistakes also help in popularizing science, as was done by my post.

Nandan

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#38

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 4:16 AM

My post at #15 , though put flippantly , was a serious question.

"The near side of the moon has fewer craters than the dark side.Is this because the earth acts as a shield ? If so, can anyone establish the frequency of meteors etc blocked by the earth."

I can find no reference to this fact. If there is an obvious answer feel free to say "it's because .......,stupid".

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#39
In reply to #38

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 4:35 AM

...near side of the moon has fewer craters than the dark side...

It seems like you have seeded an answer within your question. If there is a near side and a dark side, and it seem like a stable situation, I'd say the moon managed to shield the earth and vice versa.

As to the frequency of occurrence: The craters evidently over-patch each other, so it would be hard to establish exactly, but even so, one can deduce their educated guess or impression http://en.wikipedia.org/wiki/Special:Search?search=moon+craters

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#40
In reply to #39

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 5:10 AM

Many thanks yuvalmate. I need to clarify my understanding of the path the moon takes around the earth (I didn't think the moon could have shielded all ares of the earth equally ), and will look up the link. I guess the earths relatively recent tectonic activity would erase any pattern ,and Pangaea floating around would somewhat complicate things. Kris.

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#41
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Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 5:38 AM

As I posted above, there is a persistent theory which says that in the earliest days of forming earth, the moon was a detached "part" of the earth mass.

(The whole of the solar system created together, by self-perpetuating series of gas clouds and mineral matter colliding into mass-centers, earth included. This precess took a few hundreds of million years, some 4 billion years ago, and to some residual extent, still continues today).

The earth was then bombarded by giant chunks, Re-melting it, then sometimes adding to its mass, sometimes partially bouncing off, each with it's own given kinetic energy.

One of those, having the rare kinetic energy to barely escape earth's gravity pull, was thrown to a high orbit, then gradually descended to it's present orbit, by the common interactive gravity pull of both earth and itself. "itself" being "Luna", our moon.

It can be generally said that all the solar system's planets have moons, and even some moons have their own moons orbiting around them, all the way down to rock-size of a few kilometers.

Some of these moons are called planets, and generally saying, all the bodies in the solar system can thus be referred to as moons orbiting our sun (Called "Sol"). It's not about names, but the solar system and a pool table have something in common: both are a vivid demonstration of Newton's genius.

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#42
In reply to #41

Addendum: Why do the Earth... Re: self-perpetuating series

03/17/2007 6:07 AM

...self-perpetuating series... (above)

The said is in the sense, that as some particles collide to stick and form a bigger mass-center, the harder this center will then pull other nearing particles, and so on...

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#43
In reply to #41

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 6:50 AM

If some chunk is removed from earth surface and thrown up very high will it not come back to earth instead of forming moon revolving around earth, if only gravitational force of attraction exist. Has anyone done mathematical simulation of such phenomenon. I feel that there must be some repulsive force in existance (similar to surface tension of liquid, which may be weaker in nature) between two objects which causes planetary motion. What we measure as Gravitational Force may be resultant of two forces i.e. true Gravitational Force and repulsive force.

If larger planet with lesser atmosphere has less mateor shower, it will support my theory.

Nandan

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#44
In reply to #43

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 7:29 AM

...will it not come back to earth...

Again, this is dependant on the initial kinetics (energy, and angular momentum) of the colliding body. We don't look at something and say "this cannot be happening", but instead, we try to reason why it is, as it is.

If the gravitational pull is the sum of a grater initial pull, minus some repulsive pull, is an existing debate since the days of Newton and Leibniz, later raised by Einstein, and even in these days, in attempt to explain the apparently expanding universe, with it's immense (and somewhat measurable) "Dark matter" mass.

"Dark Matter" in this context, being anything from free floating Nucleons, to un-bound sub particles, to Einstein's repulsive "constant" (a mathematical entity, meant to complete his calculations, to reflect the apparent reality), to a missing part of our understanding of what gravity really is.

This "repulsive force" is indeed present in the background of the cosmologist's thought, but not yet decided.

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#45
In reply to #44

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 8:20 AM

I feel third entity like dark matter cannot cause planetary motion as it would be independent of the forces of two objects. Instead repulsive force should be the property of two objects forming planetary motion. Repulsive force for Venus to cause planetory motion around sun would be different than that for moon around Earth.

Again, this is not very studied statement and afraid will not disturb anyone.

Nandan

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#46
In reply to #45

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 8:35 AM

...repulsive force should be the property of two objects forming planetary motion...

This indeed is what's at stake here, to explain why isn't there a greater gravitational universal-pool, given the apparent presence of dark matter, thus determine the universe's aftermath: to reverse the current expansion and start collapsing, or to keep expanding to eternity

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#47
In reply to #43

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 12:26 PM

Nandan,

The concept is that the chunk of matter expelled from the earth in the collision that became the moon was imparted a velocity sufficient to cause the moon to orbit the earth rather than fall back into it.

I know that in fact many mathematical (computer based) simulations have been done that seem to bear this out in great detail.

Regards, Greg

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#48
In reply to #40

Re: Why do the Earth and the Moon Spin Synchronously?

03/17/2007 12:29 PM

You may want to download this NASA orbital simulator called Celestia. Here's one link (not the official, but better in related contents):

http://celestia.h-schmidt.net/earth-vt/

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#49
In reply to #48

Addendum: Celestia the app, Download, Re: Why do the Earth...

03/17/2007 5:46 PM

The application may be downloaded from:

http://www.shatters.net/celestia/download.html

This app allows you to create snapshots, and *.avi 3D animated sequences. You can also accelerate the clock to see fast moving orbits, or set the clock to any time in history to see past and future positions

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#50

Re: Why do the Earth and the Moon Spin Synchronously?

03/20/2007 5:53 AM

I couldn't copy this all that well , but it may help.

The earth and moon move around their common centre of gravity ('barycentre'). This has the odd consequence that the moons orbit around the sun is a continually concave path (imagine the sprocket on a bicycle wheel) .The moons day and night are about 2 weeks long long each. The image and info was lifted from "Moon flight Atlas" by Patrick Moore , who knows a lot more than I ever will on this topic.

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#51
In reply to #50

Re: Why do the Earth and the Moon Spin Synchronously?

03/21/2007 3:09 AM

Thanks Kris

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#52
In reply to #50

Re: Why do the Earth and the Moon Spin Synchronously?

03/21/2007 3:26 AM

The sprocket wheel above - turn its profile inside out.Sorry for confusion folks.

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#53
In reply to #27

Re: Synchronization of Earth & Moon spin

03/22/2007 8:01 PM

So What !!!

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#54
In reply to #53

Re: Synchronization of Earth & Moon spin

03/23/2007 1:33 AM

...So What !!!...

So that you don't attempt to replace someone else's manner with yours. That's his way of expression, and if you have yours, use it to the best of your purpose as you can.

I'm here to exchange my limited understanding with someone else. If they lash at me for their reasons, fine, this lash alone does not change my understanding. Only relating to his presented issues may or may not do it. They know it too.

Who cares if someone if grumpy or cheerful. Does it change the validity of their case? No. Only their argument does.

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