Late this morning, Earth’s orbit around the sun brought it to the equinoctial point. Today the sun rises due east and sets due west. But despite the etymological indication of “equal night,” day length and night length are only approximately equal today. (For more on this, see my post from 2009.) How closely equal they are depends on your latitude. For my latitude (around 26°N), the day is about eight minutes longer than the night today, but by the 27th sunrise and sunset will be exactly 12 hours apart.
In Los Angeles, about 8 degrees farther north, today is 4 minutes shorter than it is here: 12 hours and 3 minutes. And, due to a quirk in timing, there is no calendar date with “exactly” equal length day and night. On September 25th, the day is 12 hours and 1 minute long, and on the 26th, it’s 11 hours and 59 minutes.
Go figure!
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