[robryk]

> Isn't the earth's eccentricity incredibly low? (To the point that human-noticeability or non-precision-machinability are out of the question?)

It's one-percentish, and causes the length of time between equinoxes to be shorter on the northern-hemisphere-winter-side by a day or so. The date scale on the model includes single-day divisions, which made me think that such accuracy was intended; perhaps I was wrong in that.