Date: Fri, 29 Mar 2002 14:04:41 -0600
Subject: Re: (urth) Blue moon
From: Adam Stephanides 

on 3/28/02 11:44 PM, Roy C. Lackey at rclackey@stic.net wrote:

> From: Adam Stephanides 
> Date: Thursday, March 28, 2002 3:19 PM
>> Suppose that they do have independent orbits.  Conjunction is every six
>> years, so six Blue years equal either five or seven Green years.  Hence the
>> time between conjunction and Gagliardo's observation is either five-sixth
> or
>> seven-sixth of a Green year.  In either case, the distance between
>> conjunction and the position Green is in at Gagliardo's observation (call
> it
>> position A) is the distance Green travels in one-sixth of a Green year.
>> 
>> Now at conjunction Green is 105,000 miles from Blue.  At position A Green
> is
>> 250,000 miles from Blue.  Hence position A cannot be more than 355,000
> miles
>> from conjunction (actually, we could get an even better estimate, but it's
>> not necessary).  If Green's orbit is approximately circular, then simple
>> geometry (think a regular hexagon) shows that Green's distance from the
>> Short Sun itself can't be more than 355,000 miles, with Blue's distance not
>> much more: that is, less than twice the distance from the Earth to the
> Moon.
>> 
>> This is impossible. [snip]
> 
> Huh? I don't follow that. Gagliardo's numbers don't say anything about the
> length of either body's solar orbit that I can see. His numbers indicate
> that at your position A the two bodies have _diverged_ by about 145,000
> miles since conjunction. In that one year interval both bodies have also
> circumnavigated the sun. Two years later Blue and Green will have attained
> maximum separation, a distance af about 540,000 miles, then start gradually
> getting closer together until the next conjunction.
> 
> In other words, for the two bodies to be in independent orbits, those orbits
> would have to be almost congruent--almost, but not quite. Think of the two
> bodies as twin planets, traveling almost in tandem around the sun. The
> attraction of one body for the other causes minor changes in their orbital
> velocities, which average out over a six-year cycle, but account for the
> fluctuation in distance between the two bodies during the cycle. Or am I
> missing something so obvious I can't see it?

I was treating Blue and Green as analogous to Earth and Venus: completely
independent orbits which remain fixed (i. e. don't oscillate).  What you
describe is more like mantis's twin moons chasing each other.

But I think it's probably hopeless to try and figure out what, if anything,
Wolfe had in mind.

--Adam


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