I looked it over, but this is not so much a question as a comment. At the bottom of that page, you say "This type motion is called regression. Again it is similar to the classic gyroscopic precession, but it is at the slower "galactic" rate, thus in the opposite direction. This motion has the consequence of causing the Moon to screw its way outward/backward."

Screw its way outward? That's just flat out wrong.

I think that that the moon landing was not real.One of my reasons are that on fox news they showed a tape of the "moon landing" and there ere no stars anywhere in sight.Also why was the flag blowing back and forth?There is no kind of atmosphere is space.You might think that there is wind up there called solar wind,but it would be strong enough to move that flag.

I think you have the wrong thread, but anyways...

See this page right here at BA.

http://www.badastronomy.com/bad/tv/foxapollo.html

It will more fully answer your questions.

Basically, stars won't show up because they are too faint and the flag 'waves' because the astronaut was moving the flag.

Kizarvexis

[quote]
On 2002-05-21 07:58, GrapesOfWrath wrote:
So it looks as if my next sentence was absolutely correct. "The major difficulty is that it causes much consternation amongst the humans who don't understand it."

By that I mean it could be either of us.



What did I say that you think is wrong?

As near as I know, all spinning things; such as gyroscopes, tops, and planets precess or advance as the normal scheme of things. During that precession there is no in or out motion. The input torque is output at 90 degrees.

The Moon regresses or moves backward, that is not a part of the normal physical laws. The Moon also moves away from the Earth "recedes" that is not a normal spining motion and it is in direct violation of the law of gravity. The Moon is following a helical path around the galaxy, hence "screwing" its way around the galaxy. Therefore the Moon is screwing its way outward and backward away from the Earth.

It seems quite straight forward (or backward as the case may be) to me. [img]/phpBB/images/smiles/icon_smile.gif[/img]




Gary

[quote]
On 2002-05-21 23:00, Gary Redmond wrote:
I'm glad you qualified that.

First of all, "precess" does not equal "advance". I know that in common use it can mean that. But this is physics, and you have to unlearn the bad habit of using Merriam-Webster to get your physics definitions. If you delete the phrase "or advance" your statement is basically correct.

What "normal physical law" are you talking about? It is fully explainable with the laws of physics, so therefore it is indeed "part of the normal physical laws."

Only if you oversimplify. At equilibrium--which the Earth/Moon system is not--you can expect low eccentricity orbits that don't increase their semi-major axes. But only for systems in equilibrium.

The Moon is receding from the Earth as a natural consequence of angular momentum being transferred to it. With more angular momentum, it seeks a greater orbital radius. This violates no laws, and is in fact predicted by Newton and Kepler.

OK, I don't even know where to start on this one. As Grape said, it's just flat out wrong. The only way I can see to get you on the right track here is to start from the beginning.
Gary, I know you think you've found a major error in the astronomy books, and that your model shows what's really going on. But you're wrong.

But every time I want to go step by step through this, you want to leap to step 7 when I'm still trying to get you to agree to step 2.

I can show that the standard model is correct with just a physics book. But I have the feeling that if I showed you, you'd just say that since it agrees with the astronomy books and not with your a priori notions that I fell into the same pit.

Please prove me wrong on this. Let's get our definitions straight, then work step by step. When we both agree on a step, then and only then can we move on to the next.

Remember, conclusions, like antique beds, are not to be jumped upon.

_________________
Jeff Schwarz
__________________________________________________
I have Invader's blood coursing through my veins
like radioactive rubber pants! The pants command
me! Do not ignore my veins!
--Invader ZIM

<font size=-1>[ This Message was edited by: Geo3gh on 2002-05-22 00:32 ]</font>

<font size=-1>[ This Message was edited by: Geo3gh on 2002-05-22 00:34 ]</font>

Geo3gh
Quote:

<HR>

Please prove me wrong on this. Let's get our definitions straight, then work step by step. When we both agree on a step, then and only then can we move on to the next.

<HR>

Excellent plan, but we sure have trouble sticking to it.

As you saw I posted the quotation from Grolier.
I believe that cleared up the "regression of nodes" "recession of nodes" problem I was having. But, it seems to have created another.



Quote:

<HR>

First of all, "precess" does not equal "advance".

<HR>


It looks like I still have a problem with my use of the word "precess". I'll admit it's tricky.



Quote:

" " " " " " " " " " " " " " " "


Copyright - 1993 Grolier Electronic Publishing, Inc.



perturbation . . .



For instance, roughly speaking, the ascending node (the point in the Moon's orbit when it crosses the plane of the Earth's equator northward) is regressing with a period of 18.6 years, and the direction of perigee is advancing with a period of 8.85 years.



" " " " " " " " " " " " " " " "



When the Grolier said: "perigee is advancing", I took that to mean that the perigee was advancing due to the physics definition of precession, or that it was precessing. I realize that the word precess is specifically used to explain the advance due to precession. So I said: "As near as I know, all spinning things; such as gyroscopes, tops, and planets precess or advance as the normal scheme of things."



If you believe that the "perigee is advancing" due to something else, that's OK. That 8.85 years seems to quick to be caused by precession alone.



I must admit I'm lazy and my English isn't all that good.





Gary

For the fun of it, let's please prove that dinosaurs once walked on Moon.

[quote]
On 2002-05-22 13:26, SiriMurthy wrote:
Oh no! Please don't do that. Let's prove that the Moon stomped all over the dinosaurs.

Has anyone figured out what killed them?

Here are my thoughts on it.
Before there was a Moon, the Earth went around the sun. As the Earth sped up and slowed down once a year, biological clocks tick-tocked once a year. To get as big as they were dinosaurs may have lived to be 1,000 years old.

Then the Moon came into orbit.

The monthly accelerations are now greater than the yearly accelerations had been. When the Moon first arrived, it went around the Earth in 21.6 days rather than 27.3. That means those bio-clocks would have ticked nearly 17 times as fast as they had. Those beasts that had lived to 1,000 years old could only live to be 60.

They couldn't get old enough to lay their eggs!

That's what really happened. Wasn't, it?


Gary

Well, the leading theory has to do with an asteroid that hit the Earth in the Meso-America. The resultant cloud of debris and ash caused a climate change the flora and fauna of the time couldn't handle so they died off.

OK, I guess you could say that the Earth speeds up and slows down in its orbit, as gets closer to and farther from the Sun. But that's not what circadian rhythms are cued to. They're cued to periods of daylight. Unless you're refering to some other rhythm than circadian?

I hope you don't mind providing some backup for that? References? Evidence based on current zoological specimens? How long does it take for a blue whale to grow to adult size? Not 1000 years.

Except for the fact that we have evidence that the Moon was in orbit way before the KT extiction event. You keep wanting to avoid that nasty fact.

No. You're really reaching here. I must admit, your claims about biological clocks make as much sense as your claims about orbital mechanics (i.e. none). At least you're consistant.


_________________
Jeff Schwarz
__________________________________________________
I have Invader's blood marching through my veins
like giant radioactive rubber pants! The pants
command me! Do not ignore my veins!
--Invader ZIM

<font size=-1>[ This Message was edited by: Geo3gh on 2002-05-26 17:39 ]</font>

Sorry. Didn't mean to get catty there.

__________________
Jeff Schwarz
__________________________________________________
Argh!! They booby-trapped their sun!!    --Invader ZIM

That's quite all right. I asked for it. I'm quite certain the Moon could never have supported the dinosaurs as SiriMurthy suggested. But, I do believe if the Moon had hit the Earth it could have caused their demise here. Einstein's relativity relates aging to acceleration so I couldn't keep myself from rambling, sorry.



Quote:

------------------------------------------------------------------------

"Except for the fact that we have evidence that the Moon was in orbit way before the KT extiction event. You keep wanting to avoid that nasty fact."

------------------------------------------------------------------------



Yes, I know about and I'm ignoring your, as you put it "nasty fact". I agree there is evidence that there were tides. Beyoud that I'm not so sure. I still think we need to prove astronomically whether the Moon could have been here more than 66 million years ago. I say it couldn't have, and I'm trying to explain why I believe that.



Can we please get back to the cause, or reason for; the Moon having a motion called regression of nodes. I have once again massaged my Regression of nodes.htm. You had said you were hung up back at Figure 4 I offered some suggestions did you make any more progress. Fig 4, and its explanation; are redundant of Fig 2.



I keep hoping that someone will offer another explanation for the regression of nodes, not hearing one we'll have to work it out. I've heard the regression called precession and we know that's wrong. I've seen it demonstrated with a hula hoop and that don't help much either. Not having the formal education I had to work it out myself. If anyone out there has a better (than my) explanation I'd like to hear it.



Gary

Are you familiar with the 7 classical orbital elements?

In a perfect two-body system, these elements will not change.

If you add a perturbing effect -- of any sort at all -- then the elements will change.

These changes are subtle, and cannot be described in simple equations. Change in the ascending node can be caused by torque (deja vu?) from a third body, or from irregularities in either of the two bodies.

The earth has a "belt" (equatorial bulge) that causes exactly such torque.

If you wish, you can consider this as a "three body problem." A perfectly spherical earth, a perfectly spherical moon, and a "belt" -- much like the armor belt around a WWII Battleship -- around the earth. That additional "body" explains a great deal of what has been perplexing this thread.

It takes math, my friend. It takes a LOT of math. Are you familiar with Larry Niven's classic science fiction novel "Ringworld?" It's quite a jolly read. And...it doesn't work. A ringworld, as he described it, is not stable.

The mathematician MacLaurin, nearly 200 years ago, proved the same for the rings of Saturn. He showed that, if the rings were solid bodies, their orbit would not be stable, and that sooner or later, the inner edge would collide with Saturn's surface.

The math? Tough. Mighty tough.

Exercise for the student: convert the 7 classical orbital elements to x,y,z and x', y', z' and t(0) coordinates. Easy? No! But within the reach of nearly anyone here? Yes.

Silas

I still think you're putting the cart before the horse.

This whole discussion reminds me of a "Bloom County" Sunday strip where Oliver comes up with his solution to Unified Field Theory. It explains everything. Only...it doesn't explain flightless waterfowl. So while he's perplexing over this, Opus the Penguin is disappearing panel by panel. Then in the last panel, Oliver realizes that he forgot to carry the 2, and Opus is alright again.

My point is, even if I could prove conclusively with math that penguins didn't exist, all we'd need to do is send me to the San Diego Zoo's penguin exhibit to show me that my math was wrong.

Maybe I did my sums wrong. Maybe the math is fine, but my initial assumptions were way off base. It doesn't matter--the model is wrong.

You agree that there is fossil evidence for tides. Good. You're just not convinced that they're LUNAR tides. Fair enough, but I think that's where we need to go, not back to the regression of nodes. From what I've read, it seems to me that the consensus is that the tides shown in the fossil record are too large to be explained by solar tides. They are consistent with tides created by the Moon.

I say this shows that we have a moon in those long off days of yore. If you'd like to argue against this conclusion, fine. But I'd like it if you argued on the basis of evidence, not conjecture. That is, not your regression of nodes web page.

__________________
Jeff Schwarz
__________________________________________________
Argh!! They booby-trapped their sun!!    --Invader ZIM

FWIW When I was in college (early '70s) I wrote a program for a Litton programable desk calculator that would calculate geocentric RA and DEC for a comet at a specified heliocentric distance from the elements of its orbit. I can testify that the math (while straight forward) is complex and I filled several pages of a lab notebook with equations. It got me an "A" for the semester, but I never did find the comet I was looking for. Found out later that the comet had faded out while inbound two orbits before and was never seen again. [img]/phpBB/images/smiles/icon_frown.gif[/img]

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

It must have been one of those quantum comets: by observing it, you disturbed its momentum... (grin!)

Silas

[quote]
On 2002-05-27 23:50, Silas wrote:

Ah ha! That is about the same time it was proven that the Moon could only have been in orbit 400,000,000 years. What you describe for the rings of Saturn is the unnatural precession I show in Fig 9 of my Regression of nodes.htm .



I've said it before, and I'll say it again. "(deja vu?)"



If "you" do the Math and screw the Moon down to the Roche limit, the time will be 400 million years give or take a little. When a moon or ring comes into orbit around a planet it does so at a given speed. The speed may be to fast or to slow, if the speed is to fast the object screws itself downward, if to slow it moves upward. The rings apparently are going to fast (precessing). Or should I say (pregressing). [img]/phpBB/images/smiles/icon_smile.gif[/img]



I took some short cuts with my calculations but the answers are the same. Did you know; with the touch of a couple of keys here you can do square root to 12 decimal places almost instantly. How long did it take with pencil and paper? Did they even have pencils 200 years ago?
Here look at this 1.414213562373, or this e = 2.718281828459, or even this e^2 = 7.389056098931, no problem.



In the machine shop or out on a vacant lot, the first thing you need is a plan or sketch of what you want to achieve. If you want a house, a sky scraper, a gear, or a threaded whatsit, you need a plan. I've been trying to draw you the plan. You keep switching to something else.



The regression of nodes. What is it?



If you don't like my picture, draw your own.

For data you have the sidereal month and the nodic month.

Draw the plan. How does it work? Draw the plan.

Yes, 4 dimensions are tough.

I have faith you can do it.

I'll give you a hint the regression of nodes has nothing to do with a fat Earth. It has to do with Newton's first law.





Gary

On 2002-05-29 11:46, Gary Redmond wrote:
Um... Nope...

MacLaurin's work shows that a disk with a hole in it is not stably-stable when orbiting around a sphere. If there is any perturbation, no matter how small, it will grow exponentially. In the simplest possible terms, it's like saying that you can't balance a broomstick vertically. In fact, you can (I've done it!) but the tiniest breath of air will unbalance it, and once it starts to tilt, all is lost: it tilts faster and faster and finally crashes to the ground.

Precession of nodes is A Different Phenomenon. A horse of a different color. Aught Else Entirely.

Precession of nodes doesn't increase exponentially. It is (or can be) stably stable over very long periods of time.

Have you given any consideration to the model I proposed to you of a three-body-problem? The Earth, the earth's equatorial "belt," and the moon? It's the single most important (if simplified) model of the issue.

Silas

Silas

Quote:

------------------------------------------------------------------------

Precession of nodes doesn't increase exponentially. It is (or can be)
stably stable over very long periods of time.

------------------------------------------------------------------------


We (you and I) stand corrected.

Back at the beginning of this thread I tried to call it the "recession of nodes". Now you're calling it the "precession of nodes". It is in-fact the regression of nodes.

The Moon's perigee precesses the nodes regress. Most likely the perigee's motion can be explained with your "three-body-problem" model.



I still believe my Regression of nodes .gif drawing is the best interpretation as to how the regression works.



You are absolutely correct the nodes motion has been stable for 65 million years. The reason of course is Newton's first law. Once put in motion a body remains in motion at the same speed. In this case the speed is that of the Moon around the Galaxy.



This may or may not help:

The Moon goes around the Earth.

The speed of that mutual rotation is fixed by the distance between them.

The Earth and the Moon, go around the Galaxy.

The speed and direction at which they do, was set at the time they were put in motion. The Earth has one speed, the Moon has a different speed.

The result of that difference is the "regression of nodes".



Gary

In the case of the moon, you are right; the nodes regress. In the case of the earth itself, however, the nodes precess. Sorry for the confusion; both are the result of the same cause: torque caused by the moon's attraction to the earth's equatorial bulge.

Nope. I see what you mean, but...nope.

If the moon and the earth were perfect spheres, the regression you describe would not happen. It is only because the earth is not a perfect sphere, but an oblate spheroid, that this regression occurs.

Your gif is nifty...but your understanding of the issue is flawed. Please don't take this as an insult; there's nothing wrong with being wrong. That's one of the best ways to learn... But, my dear sir, you have a little learning to do...

Do you have a college-level Astronomy 101 textbook? I have several... I'm very fond of Abell and of Hartmann, each of whom has written such a textbook. May I offer to xerox the relevant pages from them and mail them to you?

(The use of the Post Office is somewhat old-fashioned in this internet age, but I don't want to post copyrighted material on the internet. Making one copy for you of only a few pages from a book is "fair use.")


Silas

<HTML>Silas

Quote:

------------------------------------------------------------------------

In the case of the moon, you are right; the nodes regress. In the case of the earth itself, however, the nodes precess. Sorry for the confusion; both are the result of the same cause: torque caused by the moon's attraction to the earth's equatorial bulge.

------------------------------------------------------------------------

I have never seen a nodic year shown. Who would know that info?



Because of the "Leap Second" I would suspect the Earth-Moon barycenter to regress around the galactic plane just as the Moon around the Earth's elliptic plane.



Or are you talking about the equinox? Or just the fact the Earth is the other half of the Earth-Moon system?



Quote:

------------------------------------------------------------------------

I'm very fond of Abell and of Hartmann, each of whom has written such a textbook. May I offer to xerox the relevant pages from them and mail them to you?

------------------------------------------------------------------------

Thank you for the offer, but I've been there done that. I'm sorry, but I'm convinced the books are wrong.



Quote:

------------------------------------------------------------------------

If the moon and the earth were perfect spheres, the regression you describe would not happen.

------------------------------------------------------------------------

Sure it would.

Please look at my Regression of nodes .gif drawing again.

Please note the orange arrow in the drawing.

Because of the regression of nodes, over 50 percent of the Moon's orbit is to the north of the barycenter elliptical plane. If as you say gravity is the force at work causing the regression, then gravity must push not pull. I'm sorry your books are wrong!

Again the Moon regresses because it travels around the Galaxy slower than the Earth does. And yes the reverse is true if the Earth travels faster then it precesses. But this is not the gyroscopic precession, and not caused by torque.





Gary



</HTML>

Oh Lordy...
Where to start??????????????
The "Leap Second" is unrelated to any of this. It is the result of difference between "time" as measured by the Earth's rotation about its axis and "time" as measured by atomic clocks.
You might as well say "Because of the "Vanilla Ice Cream" I would suspect the Sirloin Steak to be medium rare just as the Pork Chops are well done.
I have read both books. In fact, the Abell book was the text book for one of my college classes. If they are wrong, then by implication, every astronomer, physicist, and mathematician since Gallileo is also wrong!

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

The first statement is true (although trivially so, since the regression is by such a very minor amount.)

The second sentence does not follow: gravity pulls, and in a well-understood fashion.

Your third sentence is argumentative.

The regression of nodes is not measured with respect to the galaxy, but to the larger "cosmic" frame of reference.

I'm sorry, but I'm going to break off conversation with you at this point. Your answers are non-responsive, evasive, and otherwise indicative of a lack of intellectual temperance. No hard feelings, but good-bye.

Silas

Gary,

But using your analogy, we're trying to describe a tire, but you keep wanting to draw a threaded whatsit.

But I do see what you mean. Let me try to at least sketch out (figuratively; I'm going to type it out not draw) what I am trying to achieve here in my conversation with you.

From reading your posts, I am convinced that the problem is in your internal definitions of physics terms like "torque." If your definitions were correct (and this is a huge IF), then I could see that maybe you'd have a case. At least I'd follow your precession of nodes argument further. I might not end up accepting it in the end anyway, but that's niether here nor there, since your definitions are not correct.

You and I do not see eye to eye on several key points of definition and assumptions. If we can't get some agreement on the assumptions and definitions of terms, then jumping into the gif you keep pointing to is destined to fail.

My plan has been to bring out each term and assumption one by one and get agreement on it, before going on to the next one. Then, once we agreed on the terms and assumptions, I'd walk you step by step on how it all fits together to make the standard model of the Earth-Moon Tidal System.

But we can only do that once we agree on our terms.

So I leave it in your court. If you wish to play by this game plan, fine. If not, tell me your game plan.

But for my plan, we can start by having you define "torque." But what I'd like from you is not a description of what you think torque is, I want a written definition from a physics book that supports your view. I gave you one that supports mine. Your turn.

__________________
Jeff Schwarz
__________________________________________________
Argh!! They booby-trapped their sun!!    --Invader ZIM

Jeff
Quote:
=====================
Your turn.
=====================

Thank you for coming to my rescue. I was about to babble on to Kaptain K, and Silas, which would most likely not have been productive.
Hummmmmmmmmmmmm?
How do I do this?
OK!

You suggest I give a written definition of "torque". I can do that.
================================================== ===========
Fundamentals of Physics Fifth Edition (c) 1974
Quote:
"In order to make this idea precise, consider a flat object (which can be treated as essentially two-dimensional) that is constrained to rotate about an axis perpendicular to the object. Then consider that a force F, which lies in the plane of the object, is applied at a point P, which is a distance r from the axis. The line r makes an angle 0 with the force F. The force F has a moment or torque about the axis that passes through the point O."
================================================== ============
That was not a definition as such, but more a description of how it works.
As you can plainly see there are two forces involved, one to rotate, and one to constrain. Torque cannot exist or continue without the constraint of the axis. For instance a pair of pliers or scissors, you constrain one handle and apply a force to the other causing torque around the pivot point.

Is that what you have in mind?

Gary

It's a good start.

I can see where the idea of a second force comes in. But I disagree that it's necessary. I think that the authors are making the disk contrained to rotate about its axis so as to make sure there is nothing else going on. When you're trying to describe a force, it's useful to get everything else you can out of the picture.

I think you're confusing a useful tool for description with what is actually needed.

Does your book have a definition? It sounds like it would be a couple of paragraphs above the one you quoted.

I'll dig through my physics book at home, and see if I can find a example of torque without the constraint. That is, where the book calls it torque, and the fixed axis is not there.

__________________
Jeff Schwarz
__________________________________________________
Argh!! They booby-trapped their sun!!    --Invader ZIM

As an aside, who is (are) the author(s) of your physics book?

__________________
Jeff Schwarz
__________________________________________________
Argh!! They booby-trapped their sun!!    --Invader ZIM

ok, here are some websites that illustrate what I'm talking about.
<ul>[*]http://theory.uwinnipeg.ca/physics/r...00000000000000 Notice that the axis of rotation while identified, is not fixed.[*]http://teacher.nsrl.rochester.edu/ph....html#Heading4 Go to section 12.3. This is an example of torque in motion. [/list]
OK, time for me to go home. I'll check in tomorrow to see your views on this.



_________________
Jeff Schwarz
__________________________________________________
I have Invader's blood marching through my veins
like giant radioactive rubber pants! The pants
command me! Do not ignore my veins!
--Invader ZIM

<font size=-1>[ This Message was edited by: Geo3gh on 2002-06-10 21:04 ]</font>

Gary,

Have you ever played air hockey?

Imagine an air hockey puck that's rectangular, rather than round (it doesn't have to be rectangular, but it might make it easier to visualize).

Now, mentally place that puck on the table, and give it a light tap with your goalie paddle. The tap should be off center, at one corner of the rectangle. That is, it should not be directed through the center of mass of the puck.

What do you think would happen?

I say, the puck would begin to move in the direction of the tap, but it would also begin to rotate. The more tangential the tap, the more spin and the less translational motion you get.

There: one force (the tap), no constraint at all on the puck, yet it starts to rotate. It has experienced torque (a force that imparts rotation).

Do you agree?

If so, I think we might be able to generalize this model into a tabletop Earth-Moon system... with a bit of imagination!

I tried that approach, weeks ago. I used a 2x4 on ice, rather than a square hockey puck, but Gary claimed admistering an off-axis push to the puck/board was an impulse and not a torque, and thus irrelevant to the question at hand. He then ignored my attempts to explain his mistake.

I can't believe this thread is still going!

Don

Sorry, Doc Don, I forgot about your 2x4-on-ice. Or maybe I remembered it vaguely when I read the definition of torque linked to above. You're quite correct, if it was rejected then, it probably won't fly now either.

Hey, if you think this thread is bad, go check out some of the "cosmicdave" topics in the Lunar Conspiracies" forum... [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

[fixed incorrect nick... doh!]


<font size=-1>[ This Message was edited by: Donnie B. on 2002-06-11 10:46 ]</font>