Another Eclipse Post. . .

As we draw closer to The Great American Eclipse of 2017, a few thoughts are percolating in my brain (which is not quite as painful as it sounds). . .

Of course, a solar eclipse happens when the moon passes between the earth and the sun, and what's so complicated about that?  But when I think about it. . . It is at least a colossal conincidence (or is it?) that the moon and the sun are almost exactly the same size, when viewed from here on earth.  The moon is about a quarter the diameter of the earth, and the sun is about 100 times bigger than Earth.  But the sun is about 400 times farther from the earth than the moon, so they look to be about the same apparent size.  If the moon were a little bit smaller, or a little farther from earth, it would never be able to cover the sun (and all eclipses would be like the one in '94 that passed near OurTown).

Eclipses always correspond with a New Moon - when the moon passes from one side of the sun (viewed from our persepctive here on earth) to the other.  In fact, if the moon's orbit were coplanar with the earth's (i.e. perfectly 'flat' to earth's orbit), every new moon would result in an eclipse.  But because the moon's orbit is tilted by 6 degrees relative to the earth's, the moon sometimes passes above the sun, sometimes below it.  If the earth were bigger (I don't really know how much bigger would be 'big enough'), then the likelihood of the moon's shadow crossing the earth would increase, and there would be more eclipses.  As it is, total eclipses occur roughly every 1-2 years, somwhere on the planet (and the fact that it's been almost 100 years for the US means we're WAY overdue) (but, to make up for it, the next one comes less than seven years from now, in April 2024). . .

So, an eclipse happens when a new moon corresponds to the moon being at a point where its orbit is crossing the earth's orbit (or at least, 'close enough' to it).  And where the eclipse falls on the surface of the earth just depends on which part of the earth is turned toward the sun at the moment.  Next week just happens to be when our turn comes up here in the good ol' USA, for the first time in virtually a century.

It blows my mind a little bit that things like eclipses are mathematically predictable, to a high degree of precision.  I mean, we know when the eclipse is going to happen and where it's going to happen.  There are published maps, showing the path of totality, and how wide it is, and which towns are in the path of totality, and which are just outside it.  If you're on the southwest side of St. Louis, you'll see the totality; if you're on the northeast side, you'll just miss it, and we know that before it even happens.  We know how the eclipse will progress across the country, starting in Oregon around 10:15 AM Pacific Time, and ending in South Carolina about an hour-and-a-half later, mid-afternoon Eastern Time.  We know that the totality will last for just longer than two minutes (two minutes and 40+ seconds in Missouri/Illinois/Kentucky, where Jenn and I will (hopefully) be).  I mean, that's knowing an awful lot about how it's all going to happen, and it was known years, even decades ago. . .

Jenn and I are laying our plans to drive down next Sunday afternoon/evening.  We'll actually be staying with an old blogger-friend who lives not too far from the path of totality (but not actually inside it), then getting up early on Monday to fight the (hopefully not TOO awful) traffic, and settle in a decently favorable location from which to track the progress.  The long-range forecast, at least as of today, is pretty favorable for good viewing.  Hopefully, it will stay that way.  Then, sometime around 1:30 or so, the lights will go out.  And that's what I'm waiting to see. . .

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And of course, there are those who are just unclear on the concept. . .

In the meantime, I'm trying not to get too irritated with Jenn singing that old Bonnie Tyler song, over and over and over and over. . .