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    Re: Selenelion, something new in eclipses
    From: Frank Reed
    Date: 2014 Oct 8, 17:24 -0700

    Don, you wrote:
    "Many of the articles that I have read this week call the selenelion a 'rare' event."

    I think you'll find that most are copies of one article (by Joe Rao). And as I said, space.com goes for exaggeration.

    You added:
    "Don't most, if not all total lunar eclipses have a narrow zone somewhere on earth where both the rising/setting sun and eclipsed moon are visible at the same time?"

    Yes, by definition. It's only interesting when the Moon is very close to 180° distance from the Sun. To make it interesting, it seems to me that some portion of the Moon should be exactly 180° away from the Sun, so the center-to-center distance should be greater than about 179.7° (this eclipse did not quite meet that condition, by the way). Off the top of my head, that's maybe 10% of lunar eclipses. Then add to that the fact that you have to have clear skies on opposing horizons. Yeah, that's probably pretty rare. In reality, I suspect that observers are willing to add it their list of "stuff I seen" with much lower restrictions, so not rare at all...

    You concluded:
    "Or does rare event mean something occurring in major US east coast cities?"

    Ha. Well, it certainly helps, doesn't it? That's a large population with the inclination and leisure time to bother with such trivial astronomical matters. And of course, space.com, which originated this story, is an English-language new source with a mostly American readership (plus small numbers of people from other countries who get really annoyed by US-centric articles!).



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