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Thread: Question on how many solar eclipses an ancient person would have seen

  1. #1
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    Question on how many solar eclipses an ancient person would have seen

    If they lived sixty years and stayed in the same area - lets say a 20 kilometer circle from where they were born?

    Total, Partial and Penumbral.

    Is there a way to estimate this?

  2. #2
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    Quote Originally Posted by Hans View Post
    If they lived sixty years and stayed in the same area - lets say a 20 kilometer circle from where they were born?

    Total, Partial and Penumbral.

    Is there a way to estimate this?
    It depends on what exactly what you want to do. If you have a specific location and time in mind this page has all eclipses going back to 2000BC.

  3. #3
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    A partial solar eclipse is a penumbral solar eclipse. Did you mean total, partial and annular?
    Sixty years isn't long enough to give a person a good chance of seeing a total or annular eclipse from a given location on the Earth's surface. Jean Meeus brute-forced the calculation using a computer and six hundred years of eclipse calculations in Mathematical Astronomy Morsels. For an average spot on the Earth's surface, he came up with a total eclipse once in 375 years, and an annular once in 224 years. These rates would be slightly increased by the fact you've given your observer a small travel radius, but I think the change would be very slight. He didn't calculate partials, which would be more frequent.

    Hiding behind that "average spot on the Earth's surface" is a distinct latitude variation, however. Total eclipses are more common in the northern hemisphere than the southern, and annular eclipses follow a J-shaped distribution--most rare at the equator, more common at higher northern latitudes, even more common at higher southern latitudes. Overall, for both kinds of central eclipse, there's about a two-fold variation with latitude, between those areas with most eclipses and those with fewest.

    Grant Hutchison

  4. #4
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    Quote Originally Posted by grant hutchison View Post
    A partial solar eclipse is a penumbral solar eclipse. Did you mean total, partial and annular?
    Sixty years isn't long enough to give a person a good chance of seeing a total or annular eclipse from a given location on the Earth's surface. Jean Meeus brute-forced the calculation using a computer and six hundred years of eclipse calculations in Mathematical Astronomy Morsels. For an average spot on the Earth's surface, he came up with a total eclipse once in 375 years, and an annular once in 224 years. These rates would be slightly increased by the fact you've given your observer a small travel radius, but I think the change would be very slight. He didn't calculate partials, which would be more frequent.

    Hiding behind that "average spot on the Earth's surface" is a distinct latitude variation, however. Total eclipses are more common in the northern hemisphere than the southern, and annular eclipses follow a J-shaped distribution--most rare at the equator, more common at higher northern latitudes, even more common at higher southern latitudes. Overall, for both kinds of central eclipse, there's about a two-fold variation with latitude, between those areas with most eclipses and those with fewest.

    Grant Hutchison
    Thanks great info!

  5. #5
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    NASA/Goddard has a nice website on the subject.

    I live outside Buffalo, NY. My kids have seen 1 solar eclipse and I believe I have seen 3. I don't think any of them were total eclipses.

    I could be misremembering or just not as observant as I should be. I am happy to report that my daughter drew a picture of one for me from images projected on a canvas, which sits next to my desk.
    Solfe

  6. #6
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    Quote Originally Posted by Solfe View Post
    NASA/Goddard has a nice website on the subject.
    That's an excellent resource. So, taking Rome as a reasonable choice and summarizing, I see that the total number of solar eclipses (including partial) is typically between 30 and 45 per century, so it seems almost certain that anyone paying close attention would have seen many of these. If we move the restriction up to "major partial" (the site uses a magnitude of 0.85 as a cutoff for what constitutes "major") or better, the rate drops to something like 4 to 8 per century. If the weather isn't cloudy, you'd probably notice one of these even if you weren't paying close attention, so a typical person seems likely to see a small number of these in their lifetime, just by chance. Total and annular eclipses are unsurprisingly much more rare, with only 11 total eclipses and 18 annular in the 4000 year span the site calculates (those numbers match grant's average figures remarkably well). So you're not that likely to see one of these unless you're lucky.
    Conserve energy. Commute with the Hamiltonian.

  7. #7
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    This is very interesting information. Somehow I didn't even think about such a pattern. But indeed, depending on the angle of view, you can see a different shadow, and therefore a different degree of eclipse. Thanks for the link, for the sake of interest I will study what kind of eclipse when it was seen.

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