Re: Hale-Bopp THEN and NOW

Article: <5euvc5$9cm@sjx-ixn5.ix.netcom.com>
From: saquo@ix.netcom.com(Nancy )
Subject: Re: Hale-Bopp THEN and NOW
Date: 25 Feb 1997 15:09:57 GMT

In article <5ej7qj$fu7@news.Hawaii.Edu> David Tholen writes:
> Nancy writes about Hyakutake:
>> These orbits may be speculative, but THE PUBLIC doesn't
>> hear about that!
>
> No, just the orbital periods are speculative. For example an
> object with a perihelion distance of 0.23 AU and an
> eccentricity of 0.99975 would have an orbital period of
> 28,000 years, but if the eccentrcity is 0.99965, the orbital
> period is only 17,000 years. As anyone can see, the orbital
> period for a nearly parabolic orbit is quite sensitive to the
> eccentricity determination; a tiny change of only 0.0001
> in the eccentricity can affect the orbital period by 40%.
> tholen@galileo.ifa.hawaii.edu

This is fascinating, especially in light of the jerking around that the mythical Hale-Bopp's orbit took. A copy of these official orbital elements, as published by the IAU, NASA, and JPL, are documented at the web site at http://www.zetatalk.com/theword/tword900.htm. Hale-Bopp's published eccentricity CHANGED from:

In your example above, you state that a full point move at the fourth position past the decimal, .0001, would affect the orbital period dramatically, by up to 40%, YET HALE-BOPP HAD .0003 CHANGE, which should have had an even greater effect! But the orbital period was given with confidence by Marsden, and has been repeated in the press and elsewhere since then. Yet that number scarsely changed! It was reported to be 4,000 years, and now Jim Scotti says 4,200 years!

.......

Washington University
Gary W. Kronk
1995 Aug. 3
C/1995 O1 (Hale-Bopp)
(Orbit on IAUC 6198)

It currently has an orbital period of about 4000 years, but the original orbit may have had a period of about 3200 years. Marsden comments that comet Hale-Bopp "is not on its first pass from the Oort Cloud." ... Marsden wrote on IAUC 6202, "Taking the situation at face value, one can note that comet C/1995 O1 is in many respects similar to the great comet C/1811 F1 (early absolute brightness, perihelion distance, orbital inclination, 3000-year revolution period, placement beyond the sun at perihelion) and may perform as spectacularly.

........

Zetatalk
1995 August 6

How has the elliptical path of Hale-Bopp been calculated, such that it simulates the elliptical path ascribed to the 12th Planet? How was the periodic nature of Hale- Bopp calculated to be close to the periodic nature of the 12th Planet? How coincidental, and the results published and seared into the memory of the populace before the data can be examined or questioned.

........

ZetaTalk
November 24, 1996

How Brian Marsden could announce the orbital period of a comet to be between 3,000 and 4,000 years, based on the orbital element calculated between 1993 and 1995, and yet the orbit of Hale-Bopp has skewed around mightily, undergoing almost daily changes, so that the unstable Hale-Bopp orbit today looks nothing like the original orbit Marsden announced and predicated upon.