[net.astro] Comets,Neptune & Orbital Mechanics??

fred@inuxe.UUCP (Fred Mendenhall) (12/16/85)

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Recently, someone posted on the net that one of the possible
comet formation theories has the comets forming inside the orbit
of Neptune and then being thrown out to form the Oort cloud.

My orbital mechanics is not very good, but if a comet was in a 
orbit inside of Neptune and perturbed out I can only see two possible
things happening. Either the comet is given Solar System escape
velocity, hence the Oort cloud doesn't form or it is thrown in a highly
elliptical orbit but that orbit will still have a perihelion well
inside the orbit of Neptune. The only way I know of to prevent the
perihelion inside of Neptune is to have a second perturbation occur
outside the Solar System and I'm not sure how that can happen often
enough to form a stable cloud material out there. This implies that the 
most of the comets in the so called Oort cloud must travel inside our 
Solar System.

Is this right or am I missing something?  More specifically, does the
theory of comet formation inside of Neptune's orbit predict the
Oort cloud starting essentially inside of it's orbit?


				Season's Greetings
				
					
				fred