grumble at wolfe comment made attached to guardianarticle

Jeff Wilson · 09 Feb 2011, 23:03 · from 2011-February.txt.gz

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From: jwilson at io.com (Jeff Wilson)
Date: Wed, 09 Feb 2011 17:03:55 -0600
Subject: (urth) grumble at wolfe comment made attached to guardianarticle
In-Reply-To: <8796D1A4C16E4AEE811726BB8FFEFD56@jill>
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Message-ID: <4D531D5B.7030105 at io.com>

On 2/9/2011 4:52 PM, Gerry Quinn wrote:
>
> From: "Jeff Wilson" <jwilson at io.com>
>> On 2/9/2011 9:59 AM, Gerry Quinn wrote:
>>> From: "Jeff Wilson" <jwilson at io.com>
>>>> On 2/9/2011 6:26 AM, Gerry Quinn wrote:
>>>
>>>>> I think horseshoes are a bit problematic. If you look at Cruithne's
>>>>> orbit, its actual distance from Earth varies on a short scale with a
>>>>> period of one year. Over a longer term, the average distance varies.
>>>>> Since Cruithne's orbital period is one year, there's no room for
>>>>> meaningful six-year conjunctions.
>>>>
>>>> That's because tiny Cruithne is too small to influence Earth in a
>>>> detectable way. Janus and Epimethius, however, are similar in mass and
>>>> do their thing in four years.
>>>
>>> But their orbital period around Saturn is only 0.7 days... so those four
>>> years are equivalent to about 2000 years on Blue!
>>
>> That may depend heavily on odd power functions, like the orbital
>> period formula earlier; the dual orbit discovery was pre-internet
>> (1978) so I'm having a devil of a time locating anything analytical
>> about it.
>
> I think it's going to be a general property of horshoe orbits that the
> period between conjunctions will be very long compared to the orbital
> period. The reason being that the two objects are essentially in the
> same orbit, albeit going a little faster or slower at times. So their
> orbital speeds cannot differ much, and can only catch up or fall behind
> over a period of many orbits.

Is there a precis somewhere of what is known astronomically about the 
B-G system?

-- 
Jeff Wilson - jwilson at io.com
Computational Intelligence Laboratory - Texas A&M Texarkana
< http://www.tamut.edu/CIL >

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