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Article: <5htr7f$obn@dfw-ixnews4.ix.netcom.com>
From: saquo@ix.netcom.com(Nancy)
Subject: Re: The MANY FACES of Hale-Bopp - ORBIT PERIOD
Date: 2 Apr 1997 14:41:51 GMT
In article <5hbojn$d5s@vixen.cso.uiuc.edu> Laurence J Koehn writes:
>> If you look out your window and see a helicopter hovering
>> 20 above the ground, and then see it move to where it is
>> hovering 40 feet above the ground, this is NOT an illusion
>> created because you can't see the helicoper from ABOVE.
>> saquo@ix.netcom.com
>
> Initially the viewer sees the comet in almost the same position
> as Jupiter, though it is really a considerable distance "behind"
> Jupiter from the viewer's perspective. Later, the viewer sees
> the comet somewhat "above" Jupiter, with a considerably
> greater separation than before, though in reality the comet is
> closer to Jupiter in actual distance. So it's quite possible that
> Hale-Bopp's distance from Jupiter decreased although the two
> looked farther apart when seen from earth.
> koehn@prairienet.org (Laurence J. Koehn)
Perhaps you haven't grasped the situations. I do understand that the orbit of Hale-Bopp could move closer or farther away during May-June, 96, but JPL's error occurred regardless of any movement toward or away from a viewer. In the analogy above, where a helicopter might move closer or farther away, the fact that it instantaneously jumped from 20 to 40 feet above the ground is the issue. IN NO WAY COULD A MOVEMENT 3 ARC MINUTES AWAY FROM JUPITER ON THE Y COORDINATE OF DECLINATION BE MISINTERPRETED. You also refer to a "decrease" in distance to Jupiter, when my point is an increase of 3 arc minutes while supposedly passing this giant.