This article was contributed by David Baumgartner as part of a local series on astronomy.
This month’s constellation of the month should be titled “Constellations that the Sun visits while heading for the Autumn Equinox.” I guess that will just have to do for now.
Since the summer solstice in June, the Sun has been moving along the part of the ecliptic that moves southward through constellations Gemini, Cancer, and Leo. So it has been slightly further south in the sky each day, and the days have been getting shorter. On Sept. 22 ( in some years Sept. 23) the sun comes to the second place where the ecliptic crosses the equator. This point is in Virgo.
At the moment of crossing the equator, the sun is overhead on the equator of the earth, so it is shining equally on the northern and southern hemispheres. And the days and nights are the same length, 12 hours each. (Equinox means “equal night”) After this, for us in the northern hemisphere, the days keep getting shorter and cooler, as winter approaches.
The words fall and autumn mean the same. Nowadays Americans use fall and British people use autumn, but most of them understand the word used by the others are much the same.
Well there you have it, if you weren’t confused before you read this, you may be more so now. I’ve read a number of views on this subject, and they all seem to differ somewhat in their own way of telling the story. So now you have my version. See if you can come up with your own twist on the Autumn Equinox.
September Sky Watch
Sept. 17: New Moon
Sept. 18: Moon is at perigee (223,123 miles from Earth)
Sept. 18: Moon passes 6° north of Mercury
Sept. 22: Autumn Equinox occurs
Sept. 23: First quarter Moon
Sept. 25: Moon passes 1.6° south of Jupiter
Sept. 25: Moon passes 2° south of Saturn
Sept. 29: Moon passed 4° south of Neptune