The length of daylight decreases rapidly during September.  At the beginning of the month, the sun is in the sky for over 13 hours.  By month’s end, the sun is above the horizon for about 11 hours, 45 minutes.  On the chart above, the sun’s yearly daylight hours is displayed in the red graph.  The blue-shaded graph shows the daylight hours during September.

The sun reaches the autumnal equinox on September 23, 2015, at 3:22 a.m. CDT.  At this time the sun’s rays shine directly on the equator.  The sun passes directly overhead at noon as seen from the equator.  Until next March, the sun’s intensity is directed toward the southern hemisphere, where the seasons are opposite of those in the northern hemisphere:  A cold and frosty day during December in Chicago is a warm, summer December day in Sydney.

Moon

Phase	Date/Time	Moonrise	Moonset
Last Quarter	09/05/15 (4:54 a.m.)	11:26 p.m. (09/04)	1:06 p.m.
New Moon	09/13 (1:41 a.m.)	6:47 a.m.	7:16 p.m.
First Quarter	09/21/15 (3:59 a.m.)	2:13 p.m.	12:18 a.m. (09/22)
Full Moon Lunar Eclipse	09/27/15 (9:50 p.m.)	6:32 p.m.	7:15 a.m. (09/28)
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

A spectacular lunar eclipse occurs on the evening of September 27 that is visible across North America.   More details in an upcoming posting.