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    Re: Origin of the analemma
    From: Frank Reed
    Date: 2011 Oct 13, 16:43 -0700

    John, you wrote:
    "I'm assuming that the classic analemmas on globes are either time averaged or the resolution is too poor to see differences in the year-to-year variations."

    Yes. On older globes, the analemma is normally symmetrical, so they didn't even try very hard.

    You wrote:
    "If you draw them large enough, the year-to-year variations begin to become apparent."

    The four-year cycle can be handled just by changing the entry time (e.g. "subtract six hours in 2012"). That's fairly good for ten or twelve years out. Beyond that, you can have a little graphic of years vs. date for the difference since the variation is fairly slow. Something color-coded would be nice. :)

    And you added:
    "Another interesting question to contemplate is the following: what do analemmas look like on other planets? It turns out there are curious variations, depending on the planet."

    Yeah, somebody displayed a Mars analemma at the "leap second" conference. This is now even in the Wikipedia article, but for a really nice source from the early days of the web, be sure to visit www.analemma.com and click on "other analemmas". Note that the "www" in this address is mandatory if you want to see the content. This web site was one of the earliest multimedia science sites, and its age really shows. Not too badly -- it's just "quaint" in its references to "Windows 95" and "Quicktime required" and the fact that it uses "frames" for its layout (a well-known SEO error ever since Google was born).

    -FER


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