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    Re: Sun goes round Earth, or something like that...
    From: Frank Reed
    Date: 2014 Feb 17, 14:21 -0800

    Don and Alex,

    Yes indeed: Sherlock Holmes! Of course Conan Doyle added this strange ignorance of basic astronomy to Sherlock to make him seem more alien, more obsessed. Today he might be diagnosed with some degree of autism and perhaps put on meds.

    Holmes (and therefore probably Conan Doyle) has a common misconception about memory. Memorizing more things does not "fill up" the brain, like a computer, and actually makes it easier to memorize even more things under many circumstances. The notion that students shouldn't be required to memorize things is a terrible error in modern education. Memorize more! Especially in an era where the Internet is always at our fingertips (I can search the web from three separate, unconnected devices within arm's reach at this moment), we need to exercise our memories regularly.

    By the way, for anyone looking for entertainment while snowed in this winter, I can recommend the BBC series "Sherlock". It's a lot of fun and a plausible modern-day take on the character.

    Alex, you wrote:
    "When we saw Copernicus monument, and I started to explain the history
    of the MONUMENT, one professor from China asked "who he is ?"...."

    Fascinating. Of course the focus on Copernicus is a unique feature of the western narrative of European scientific history. Knowledge of Copernicus does not add in the slightest way to an understanding of astronomy. But it sure helps with the metaphors when people start talking about the latest 'Copernican revolution'. Copernicus, like Bowditch in our small specialty, is credited with far more than he deserves. Copernicus IS that monument you visited.

    You concluded:
    "Actually the results of the poll you mention are not that shocking
    on my point of view. Is it really an important difference, what rotates
    about what? "

    Yes, I agree. That's part of what I meant about it being a measure of scientific "literacy". It's something we've all been exposed to and should be able to recall. But it has precious little practical value. And in fact, I suspect that the real numbers of people who do not actually know this are considerably smaller than the survey says. There are always people who get the most basic questions wrong in surveys. It doesn't mean they are literally that ignorant. There can be many explanations, not limited to the few I already suggested.

    Of course the Earth really does revolve around the Sun. Brad and Lu mentioned the Sun-Earth barycenter but that's a tiny correction (300 miles from the center still leaves the Earth orbiting "around the Sun" --ever so slightly off-center). Roughly ten times larger is the wobbly motion caused by the Moon tugging the Earth (and the two of them orbiting their common barycenter). That makes the Earth's orbit a sort of smoothed dodecahedron. But they're all small corrections. Yet it's still really very tough to come up with a logically "secure" and rigorous statement on this issue. What does the statement "the Earth revolves around the Sun" actually mean? "Revolves around" implies a path with certain bounds in radial distance (never closer than some distance, never further than some other) and a degree of stability of this motion over relatively long time periods. It also implies a cyclic and regular motion --no backing up! But it certainly doesn't imply Keplerian ellipses or anything more specific. In the infinite set of all possible motions over infinite time, "revolves around the Sun" appears to select a rather small subset, but in reality it is a vague, verbal condition with a lot of room for "wobble".

    Here's one to contemplate: does the Moon orbit the Earth primarily with the Sun slightly perturbing its path around the Sun? Or does the Moon orbit the Sun primarily, and the Earth just happens to be synchronized with it, with the Earth and Moon slightly perturbing each other's solar orbits?


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