Monday, March 20, 2006

I can't forget to turn the earth so both sides get their share of darkness and of light

Today, at 1:26 PM EST, was the vernal equinox!!! (I was going to wear one black sock and one white sock today, but I forgot.)

"Equinox" means "equal night", and if the earth were perfectly spherical and had no atmosphere, then there would have been exactly 12 hours of daylight and 12 hours of night today everywhere on earth. In fact, sunrise in NYC was at 6:00 AM, and sunset was at 6:08 PM. The extra 8 minutes are because the atmosphere refracts the sun's light so that we can still see the sun for about, oh, 4 minutes before we would otherwise see it rise, and about 4 minutes after we would otherwise see it set.

At 1:26 PM today, the sun was directly overhead at the equator. From now until the autumnal equinox (12:03 AM EDT, September 23, 2006), the sun will be directly overhead at various points north of the equator, as the northern hemisphere heads toward summer.

Everywhere on Earth today, the sun rose in the east and set in the west. Like, really really east and west. From now until September, the sun will rise slightly north of east, and set slightly north of west. (However, everywhere north of the Tropic of Cancer, the sun will always make it to the southern half of the sky by noon.)

No, you can't balance an egg on its end today, or no more easily than any other day, anyway.

In the equatorial coordinate system, the sun is at right ascension 0 today.

If we weren't still stuck with the Julian calendar, today would be tekufat Nisan.

It's spring!

1 comment:

  1. Thanks for this cool post!

    Today is also my birthday, so I love equinoctial trivia. :-)