Looking for a brief explanation of the autumnal equinox on Saturday, September 22nd?
For an instant, the plane of the equinoctial colure will be perpendicular to the earth’s orbital radius vector.
Simple as that!
Curmudgeon at Large
Short bursts of curmudgeonry on any topic.
Curmudgeon at Large 
Or, more simply, that time of year when the sun shines most directly into your eyes as you travel east or west in the afternoon (fall) or morning (spring)!
Yes, also known as highway stonehenge.
Got it.
Good.