Fergie's Tech Blog

Autumn Arrives Tonight in Northern Hemisphere

Illumination of Earth by Sun on the day of equinox (vernal and autumnal).
Image source: Przemyslaw "Blueshade" Idzkiewicz / Wikipedia

Autumn arrives in the northern hemisphere tonight, as the Sun crosses the equator on its journey southward. Autumn officially begins at [9:03 p.m. Pacific Daylight Time] -- the moment of the September equinox.

The equinoxes and solstices represent the start of the seasons as measured astronomically. At the solstices, the Sun is farthest north or south in the sky for the year. And at the equinoxes, it's half-way between. The Sun rises due east and sets due west on the equinoxes across the entire globe -- the only times of year for which that's true. And day and night are of roughly equal length on the equinoxes.

posted by Fergie @ 9/22/2006 01:33:00 PM