It might be relevant that, according to rumor, the years of the various planets have ratios that are approximately rational with small denominators. Seems that a random solar system is likely to approach one like this for stability reasons. (But I don't have documentation.) --Dan << My brother is interested in building an orrery, and posed the following (somewhat ill-defined) problem: given a bag of gears and a set of periods, how do you partition them to get the best set of gear chains? Continued fractions, of course, give the best rational approximations to a given period, but that assumes you can choose the number of teeth.

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_____________________________________________________________________ "It don't mean a thing if it ain't got that certain je ne sais quoi." --Peter Schickele