22 September 2008


I looked outside early this cool (40 Fahrenheit!) morning and the moon--at Last Quarter--was nearly overhead. The morning twilight obscured the nearby stars, but my Sky Calendar says they would have been Castor and Pollux, the twins of Gemini. Today is the AUTUMNAL EQUINOX. "Autumnal" is a lovely word, eh? My authority for such matters is the venerable United Stated Naval Observatory, and their Earth's Seasons page. According to the site, the Autumnal Equinox begins today at 15h 44m Universal Time. For Pacific Daylight Time, subtract seven hours--thus the equinox occurs for me at 8:44 a.m. My reference to UT means Coordinated Universal Time, that is the time kept by cesium clocks and referenced to the Greenwich Meridian (zero degrees longitude). "True" Universal Time, called "UT1" by astronomers and navigators, is a direct measurement of the the sun's position or "hour angle." Clocks, of course, are human devices, and do not account for the vagaries of nature (q.v. UT). The earth and sun move merrily on their own ways despite how we describe, measure, and catalog them. Speaking of moving--I'd better. The clock at work ticks inexorably, like they all do. Wouldn't do for the teacher to be late.

1 comment:

nancyo said...

'Autumnal' is indeed lovely, even hymnal! My soul sings on this day; it is the gentle beginning of the warmest, mellowest, really the truest time of celebration of MY year, anyway. I want to be like Snoopy and run and jump into a pile of leaves.