(urth) grumble at wolfe comment made attached to guardianarticle

[Jack Smith]

I like this explanation, but I don't think it would work.  For bodies in
orbit around a central body, the orbital period is directly proportional to
the distance or radius from the central body.  So if Green orbits in 6/7 of
a Blue year, then Green must be 6/7 of Blue's distance from the sun.  If
Blue is 90 million miles from the sun, then Green must orbit at  77 million
miles radius, which makes Green 13 million miles from Blue at closest
approach.  But we know that at conjunction the 2 planets are only 35,000
leagues (105,000 miles) apart (In Green's Jungles, ch. 15).

On Tue, Feb 8, 2011 at 9:38 PM, Gerry Quinn <gerryq at indigo.ie> wrote:

>
> It can work if they have circular orbits that are quite close together, so
> that Green orbits their star in 6/7 of a Blue year.  Green will go around
> the star slightly faster than Blue, so that Blue is falling further and
> further behind.  After 6 Blue years, Blue will have made 6 orbits, while
> Green will have made 7 and caught up on Blue from behind.
>
> I don't know if two large planets with such similar orbital radii  would be
> stable, but anyway it would fit the conjunction schedule, and Green would be
> a bit hotter than Blue (their temperatures would also depend on atmospheric
> composition).
>
> - Gerry Quinn
>
>
> ----- Original Message -----
> *From:* Jack Smith <jack.smith.1946 at gmail.com>
> *To:* The Urth Mailing List <urth at lists.urth.net>
> *Sent:* Wednesday, February 09, 2011 1:47 AM
> *Subject:* Re: (urth) grumble at wolfe comment made attached to
> guardianarticle
>
> "BTW, is there a consensus on the exact relation of the planets Blue and
> Green? Do they orbit one another as a single system, or do they orbit the
> sun on opposite sides, as do Earth and Gor?"
>
> They can't orbit each other or orbit on opposite sides of the sun because
> Blue and Green  are farther apart and then get closer at conjunction.
>  Conjunction occurs every 6 years (OBW, Ch 7), and Blue's year seems to be
> about the same as a year on the Whorl.
>
> I'm not sure how Blue and Green move to produce this conjunction.  If they
> are about the same distance from the sun but in different orbital planes,
> they could at times be closer or more distant but conjunction would occur
> twice a year.  Perhaps Blue's orbit is circular and Green's is more
> eliptical, resulting in the 6 year interval, but I haven't been able to
> figure how this would work.
>
>
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-- 
Best wishes,
Jack
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