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Complex Numbers #569023 added February 20, 2008 at 10:34pm
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Dark Side of the Moon
http://antwrp.gsfc.nasa.gov/apod/ap080220.html
I was concerned, today, that the cloud cover would preclude my viewing of the total eclipse of the moon this evening. As with much in life, I hoped for the best but prepared for the worst... but it's a wonderfully clear night, and the moon around 8:30 looked like it had a big chunk bitten out of it.
It's at the times of eclipse that I can best visualize how the solar system is put together. In this case, we're treated to a view of Saturn just a few moon-widths away (the moon subtends an arc of 0.5 degrees of sky; thus, two moon-widths is about one degree of arc. There are, of course, about 180 degrees of arc across the visible celestial equator, and a total of 360 degrees, corresponding to 360 degrees of longitude. Why 360? Largely because there are 365 days in a year, and 360 is the closest number with many factors.
They came up with that system in ancient Babylon, or perhaps inherited it from an even older culture. The ancients were pretty good with numbers, but fractions sometimes stumped them; hence, they looked for numbers that were easily divided. That's why there's 24 hours in a day instead of some multiple of 10; it's divisible by 1, 2, 3, 4, 6, 8, 12 and, of course, itself. 24 itself goes neatly into 360. And then there's the mystery of why there are seven days in a "week" and not six or eight; I think that calendar evolved separately from the solar calendar, as weeks of seven days work relatively well in marking off lunar cycles. Perhaps, long ago, weeks alternated between seven and eight days, before some bright caveperson noticed: seven days in a week; seven moving celestial bodies. Coincidence? He or she didn't think so. And so the days of the week took on the attributes of the Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn (in that order), disengaging the week from its relationship to the moon. Just a thought I had; I don't know if there's any reality to it.
On a more personal note, things are starting to turn around a bit, for me. My back continues to improve. We're starting to get some jobs dribbling in at the office. My dad's going to be released from the hospital soon, perhaps even tomorrow, to go back to his assisted-living place - though he'll require more nursing care.
Well, time to go check on the moon again - it should be at its darkest right about now. It can only get brighter from here. |
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