Thanks for the link to horseshoe orbits!  This might work.<div><br><br><div class="gmail_quote">On Wed, Feb 9, 2011 at 12:33 AM, Jeff Wilson <span dir="ltr"><<a href="mailto:jwilson@io.com">jwilson@io.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im">On 2/8/2011 9:36 PM, Gerry Quinn wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I forgot about that.<br>
But one or both could have an elliptical orbit.<br>
Again, I don't know whether precession would make this unrealistic or<br>
not. And 35000 leagues is incredibly, dangerously close for two<br>
Earth-sized planets.<br>
But in terms of basic mechanics, a series of conjunctions should be<br>
possible (for story purposes, I think it would probably be sufficient if<br>
the series lasted a few centuries).<br>
</blockquote>
<br></div>
They could be paired in a horseshoe orbit:<br>
<br>
<a href="http://curious.astro.cornell.edu/question.php?number=210" target="_blank">http://curious.astro.cornell.edu/question.php?number=210</a><br><font color="#888888">
<br>
-- <br>
Jeff Wilson - <a href="mailto:jwilson@io.com" target="_blank">jwilson@io.com</a><br>
Computational Intelligence Laboratory - Texas A&M Texarkana<br>
< <a href="http://www.tamut.edu/CIL" target="_blank">http://www.tamut.edu/CIL</a> ></font><div><div></div><div class="h5"><br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Best wishes,<br>Jack<br>
</div>