Angular acceleration of the earth

The explaination you made about Jupiter moving the sun clearly said the center of the sun is what is being moved. This is not a trivial issue and I hope you at least agree with me on that.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Jim]: The explanation you made about Jupiter moving the sun clearly said the center of the sun is what is being moved.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

One problem here Jim is that I always have to guess what you mean because you don't use the words of the field in an unambiguous way. When we have two or more bodies, each one has its own center of mass, each pair has another center of mass, and the group of bodies as a whole has another center of mass. You didn't specify which one you were asking about, so I guessed that you meant the center of mass of pairs or groups of bodies. But apparently, you were only interested in the center of mass of the Sun.

You now know Newton's universal law of gravitation. The Sun attracts Jupiter, and Jupiter attracts the Sun. The mass of the Sun is 1000 times greater than the mass of Jupiter. So the Sun's effect on Jupiter is 1000 times greater than is Jupiter's effect on the Sun.

To put that into numbers, the Sun makes Jupiter orbit in a circle (approximately) with a radius of 5 au, or roughly 750 million kilometers. Jupiter makes the Sun orbit in a circle 1000 times smaller, with a radius of 0.005 au or 750 thousand kilometers.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>This is not a trivial issue and I hope you at least agree with me on that.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

No, I do not agree with you, and would classify this as a trivial issue. Because every body attracts every other body, the Sun cannot be immune. It is not somehow anchored in space so that it can resist the pull of Jupiter. You seem to think that some bodies are immune from the effects of gravity. I don't know why you think that, but it is certainly not the case. Get an elementary astronomy book, learn what a "transit circle" (a special kind of telescope) is, and how it easily measures the Sun's motions in response to Jupiter and to each of the other planets. -|Tom|-

I do not think any such thing and you have no reason to accuse me of having that belief. But, if you think it is trival then there is no point continuing this with you anyway.

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<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Me]Comets have highly elliptical orbits around our sun so how do they stay within our solar system each cycle when they should fly off into space never to return?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

An ellipse is a closed, periodic orbit. So I don't understand your question. Comets do not come anywhere near any other star, not even the nearest other star (Proxima Centauri). -|Tom|-
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...*...............................................................................................*...
.*..<b>O</b>.............................p.............................................................X..*.
...*...............................................................................................*...
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Excuse the crude "drawing" above but i dont know how to insert images from word.


O = equals our sun
* = typical orbit path of a comet ( very distant one )
p = pluto
. = ignore this i needed these for formatting

X - What is here to make the comet return on its elliptical orbit when i would have thought it should keep on going in a straight line and never to return?

thanks-forever learning
david

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[kingdavid]: X - What is here to make the comet return on its elliptical orbit when i would have thought it should keep on going in a straight line and never to return?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

The Sun's gravity is there. What is the difference in kind between X and p? If p doesn't keep going forever, why should X? Gravity from the Sun never ceases at any distance. It just gets so weak that at great distances, other sources of gravity (e.g., from other stars) overwhelm it. -|Tom|-

The reason the comet returns is explained in Kepler's third law. If you use that on an orbit with zero angular momentum the comet or whatever goes only so far and comes to a stop. It then returns by the same route. Its a matter of doing the math.