Re: Planet Definition revised


James Nicoll wrote:
In article <1156352405.790447.282780@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Eric Chomko <pne.chomko@xxxxxxxxxxx> wrote:

James Nicoll wrote:
In article <1156318353.296230.103970@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
steve <stephen.colbourne@xxxxxxxxxxxxxxx> wrote:
See:-

http://www.space.com/scienceastronomy/060819_new_proposal.html

It is proposed that part of the planet definition should be a
requirement that :-

(a) is by far the largest object in its local population[1],
[1] The local population is the collection of objects that cross or
close approach the orbit of the body in consideration.


I can see that Pluto would by this lose its right to being a planet due
to Neptune.

Pluto never gets closer to Neptune than about 20 AU.

Never? You are aware that during 1979-1999 Pluto was actually closer to
the Sun than Neptune was, right?

I am closer to the North Pole than you are and have been closer to
South Pole than you are and yet I am not close to you and never have been.
The Earth is surprisingly large and the solar system is even bigger.

Pluto and Neptune's orbits are such that they never approach
the same region of space at the same time. This is not a coincidence,
because bodies like Pluto with orbits that did get close to Neptune
got ejected (Or in the case of Triton, captured) from the Solar System.

So you KNOW that if Neptune and Pluto were to come into a collision
course some day when Pluto's argument of ascending node and position
aligned with that of Neptune's orbital position (or anything close -
i.e. much less than even 20 AU!) that the result would be an ejection
and not a capture or some other gravitational disturbance of attraction
(maybe some orbital perturbance)? Wow, do you have a crystal ball?
Seriously, how can you make that statement given what we know of their
orbital characteristics? Take a look at this diagram:
http://ssd.jpl.nasa.gov/?ss_outer

Also, note that Neptune on average is 30 AUs and Pluto is 39 AUs. Are
you saying that they have no synodic period? Becuse if they do have a
synodic period, the they are ~9 AUs from one another, BY DEFINITION,
each time!

In fact, I'm looking into when the alignment occurred where all planets
were in the same quadrant of the soalar system back in March of 1983 to
see if Pluto and Neptune were within 20 AU at that time.

Eric



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