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).<br>
<br><div class="gmail_quote">On Tue, Feb 8, 2011 at 9:38 PM, Gerry Quinn <span dir="ltr"><<a href="mailto:gerryq@indigo.ie">gerryq@indigo.ie</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div bgcolor="#ffffff">
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">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.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">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).</font></div>
<div><font size="2" face="Arial"></font> </div><font color="#888888">
<div><font size="2" face="Arial">- Gerry Quinn</font></div></font><div class="im">
<div><font size="2" face="Arial"></font> </div>
<blockquote style="border-left:#000000 2px solid;padding-left:5px;padding-right:0px;margin-left:5px;margin-right:0px">
<div style="font:10pt arial">----- Original Message ----- </div>
<div style="font:10pt arial;background:#e4e4e4"><b>From:</b>
<a title="jack.smith.1946@gmail.com" href="mailto:jack.smith.1946@gmail.com" target="_blank">Jack Smith</a> </div>
<div style="font:10pt arial"><b>To:</b> <a title="urth@lists.urth.net" href="mailto:urth@lists.urth.net" target="_blank">The Urth Mailing List</a> </div>
<div style="font:10pt arial"><b>Sent:</b> Wednesday, February 09, 2011 1:47
AM</div>
<div style="font:10pt arial"><b>Subject:</b> Re: (urth) grumble at wolfe
comment made attached to guardianarticle</div>
<div><br></div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:9px">"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?"</span>
<div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:9px"><br></span></div>
<div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:9px">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.</span></div>
<div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:9px"><br></span></div>
<div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:9px">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.<br></span><br></div></blockquote></div></div>
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