Sunday, September 23, 2007 2:36:20 AM Autumnal Equinox The sun, our most powerful nuclear reactor, the source of heat and light for all life on Earth, does something very prosperous and in tune with Nature on this day. It goes south for the winter. This year the sun officially crosses the line at 09.51 GMT, or 2:51 am PDT. As we always celebrate crossing the equator, today is by itself a cause for celebration. Astronomically, it's the first day of Fall. As summer has now ended, harvests include barley, hazelnuts, blackberries, and of course grapes. Not much is remembered about this day in the Celtic calendar, but if you've ever been to Munich for the Oktoberfest you get an idea of how the Celts did it right. The Welsh called this day Alban Elfed. Remember Wales? King Arthur, Merlin, Avalon, the Battle of Angelsey, and all that?