Angular acceleration of the earth

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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 thatm at great distances, other sources of gravity (e.g., from other stars) overwhelm it. -|Tom|-
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yes but p or any other planet is not in an erratically elliptical orbit like the comet and the comet due to a slingshot effect (speeds up as it orbits nearest to sun) would be speeding away directly from the sun. so why would the comet seemingly turn around at a certain far distant point and then repeat its elliptical orbit?

p does go on "forever"-forever around the sun, but the comet should also go on "forever" in a straight line after the "sling-shot" effect-i am also assuming-maybe incorrectly that these comets are travelling at near or greater than the suns escape velocity when they are travelling away from it.

david-learning

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[kingdavid]: yes but p or any other planet is not in an erratically elliptical orbit like the comet<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

The comet is in a simple elliptical orbit too, not an "erratic" one. It is just a higher-eccentricity (longer) ellipse.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>and the comet due to a slingshot effect (speeds up as it orbits nearest to sun) would be speeding away directly from the sun.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

It cannot be speeding "directly away from the Sun" unless it was ejected from the Sun. It is moving on a very long ellipse that will eventually round the far end and start heading back. The curvature of both ends of the ellipse is the same.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>so why would the comet seemingly turn around at a certain far distant point and then repeat its elliptical orbit?<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. It works the same way for large ellipses (comets) as for small ellipses (planets). To better understand the physics of orbits, read chapter six of <i>Dark Matter, Missing Planets and New Comets</i>.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>i am also assuming-maybe incorrectly that these comets are travelling at near or greater than the suns escape velocity when they are travelling away from it.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

Yes, <i>near</i> the escape velocity, but not at it. At escape velocity, the orbit becomes a parabola and does go on forever, and can never return. Some comets do get into parabolic or even slightly hyperbolic orbits by being pulled slightly above escape velocity by the tug of planets (usually Jupiter). But all periodic comets, by definition, are on ellipses that repeat their paths just as planets do. -|Tom|-

From the perspective of the sun the comet is moving in and out from the sun along radials and the sun does not observe the angular motion as an observer outside does.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Jim]: From the perspective of the sun the comet is moving in and out from the sun along radials and the sun does not observe the angular motion as an observer outside does.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

That is false. -|Tom|-

comets have not reached/passed the suns own escape velocity-thats why comets are still there-cheers tom

dave

The false statement above is the result of putting the finger I type with in gear before engaging the brain. It is quite a confusing statement even if I know what I meant.