Home > Ephemeris Program, Month preview > 08/31/2021 – Ephemeris – Previewing September skies

08/31/2021 – Ephemeris – Previewing September skies

August 31, 2021

This is Bob Moler with Ephemeris for Tuesday, August 31st. Today the Sun will be up for 13 hours and 16 minutes, setting at 8:20, and it will rise tomorrow at 7:05. The Moon, 1 day past last quarter, will rise at 1:07 tomorrow morning.

Let’s look at the skies for the month of September. The sun will be moving at its greatest speed in its retreat to the south. Daylight hours in the Interlochen/Traverse City area and will drop from 13 hours and 13 minutes tomorrow to 11 hours and 44 minutes on the 30th. The altitude of the Sun above the southern horizon at local noon will be 54 degrees tomorrow, and will descend to 42 degrees on the 30th. Local noon at mid-month will be around 1:37 pm. The season of summer is getting short, so enjoy it while you can. Summer ends and autumn begins at 3:21 p.m. on September 22nd, the autumnal equinox. This year the Harvest Moon, the nearest full moon to the equinox, will fall two days before it on the 20th.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

September Star Chart

September Evening Star Chart

Star Chart for September 2021. Created using my LookingUp program. Click on the image to enlarge it. Created using my LookingUp program.

The planets and stars are plotted for the 15th at 10 p.m. EDT in the evening and 6 a.m. for the morning chart. These are the chart times. Note that Traverse City is located approximately 45 minutes behind our time meridian, West 75° longitude. (An hour 45 minutes behind our daylight saving time meridian during EDT). To duplicate the star positions on a planisphere you may have to set it to 1 hour 45 minutes earlier than the current time.

September Morning Star Chart

September Morning Star Chart

Star Chart for September 2021 (10 p.m. EDT, September 15, 2021). Click on the image to enlarge it. Created using my LookingUp program.

For a list of constellation names to go with the abbreviations, click here.

  • Pointer stars at the front of the bowl of the Big Dipper point to Polaris, the North Star.
  • Leaky dipper drips on Leo.
  • Follow the arc of the handle of the Big Dipper to the star Arcturus.
  • The Summer Triangle is in red.

Twilight Limits, Nautical and Astronomical

      EDT        
  Morning Twilight Evening Twilight Dark Night Moon
Date Astro. Nautical Nautical Astro. Start End Illum.
2021-09-01 5h26m 6h04m 21h28m 22h06m 22h06m 1h07m 0.24
2021-09-02 5h28m 6h06m 21h26m 22h04m 22h04m 1h57m 0.16
2021-09-03 5h29m 6h07m 21h24m 22h02m 22h02m 2h55m 0.09
2021-09-04 5h31m 6h08m 21h22m 22h00m 22h00m 4h01m 0.04
2021-09-05 5h32m 6h10m 21h20m 21h57m 21h57m 5h11m 0.01
2021-09-06 5h34m 6h11m 21h18m 21h55m 21h55m 5h34m 0
2021-09-07 5h35m 6h12m 21h16m 21h53m 21h53m 5h35m 0.02
2021-09-08 5h37m 6h14m 21h14m 21h51m 21h51m 5h37m 0.06
2021-09-09 5h38m 6h15m 21h12m 21h49m 21h49m 5h38m 0.13
2021-09-10 5h40m 6h16m 21h10m 21h46m 22h06m 5h40m 0.21
2021-09-11 5h41m 6h18m 21h08m 21h44m 22h35m 5h41m 0.32
2021-09-12 5h43m 6h19m 21h06m 21h42m 23h12m 5h43m 0.43
2021-09-13 5h44m 6h20m 21h04m 21h40m 23h57m 5h44m 0.54
2021-09-14 5h46m 6h22m 21h02m 21h38m 5h46m 0.65
2021-09-15 5h47m 6h23m 21h00m 21h36m 0h53m 5h47m 0.76
2021-09-16 5h48m 6h24m 20h58m 21h34m 1h59m 5h48m 0.84
2021-09-17 5h50m 6h25m 20h56m 21h31m 3h10m 5h50m 0.91
2021-09-18 5h51m 6h27m 20h54m 21h29m 4h24m 5h51m 0.96
2021-09-19 5h53m 6h28m 20h52m 21h27m 5h37m 5h53m 0.99
2021-09-20 5h54m 6h29m 20h50m 21h25m 1
2021-09-21 5h55m 6h31m 20h48m 21h23m 0.99
2021-09-22 5h57m 6h32m 20h46m 21h21m 0.95
2021-09-23 5h58m 6h33m 20h44m 21h19m 0.9
2021-09-24 6h00m 6h34m 20h42m 21h17m 21h17m 21h26m 0.84
2021-09-25 6h01m 6h36m 20h40m 21h15m 21h15m 21h52m 0.76
2021-09-26 6h02m 6h37m 20h38m 21h13m 21h13m 22h23m 0.67
2021-09-27 6h04m 6h38m 20h36m 21h11m 21h11m 23h00m 0.58
2021-09-28 6h05m 6h39m 20h34m 21h09m 21h09m 23h46m 0.49
2021-09-29 6h06m 6h41m 20h32m 21h07m 21h07m 0.39
2021-09-30 6h07m 6h42m 20h31m 21h05m 21h05m 0h40m 0.3

Twilight calendar was generated using Cartes du Ciel (Sky Charts).

See my blog post: Twilight Zone for the definitions of the different periods of twilight here: https://bobmoler.wordpress.com/2018/09/27/.

NASA Calendar of Planetary Events

Sep  1  We            Venus: 39.9° E
     1  We   8:23 pm  Moon North Dec.: 25.9° N
     4  Sa  12:07 am  Moon-Beehive: 3.1° S
     5  Su  10:32 am  Venus-Spica: 1.6° N
     6  Mo   8:52 pm  New Moon
     9  Th  10:09 pm  Moon-Venus: 4.1° S
    11  Sa   6:06 am  Moon Perigee: 368500 km
    12  Su  12:35 pm  Moon Descending Node
    13  Mo   4:39 pm  First Quarter
    13  Mo  11:59 pm  Mercury Elongation: 26.8° E
    14  Tu   4:10 am  Neptune Opposition
    14  Tu  11:48 pm  Moon South Dec.: 26° S
    16  Th  10:37 pm  Moon-Saturn: 3.9° N
    18  Sa   2:50 am  Moon-Jupiter: 4.1° N
    20  Mo   7:55 pm  Full Moon, Harvest Moon 
    20  Mo  10:03 pm  Mercury-Spica: 1.4° S
    22  We   3:21 pm  Autumnal Equinox
    26  Su   3:33 am  Moon Ascending Node
    26  Su   5:44 pm  Moon Apogee: 404600 km
    28  Tu   9:57 pm  Last Quarter
    29  We   4:26 am  Moon North Dec.: 26.1° N
Oct  1  Fr            Venus: 44.9° E

All event times are given for UTC-4 hr: Eastern Daylight Saving Time.

Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC),
http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html.

If you go to the above site, you can print out a list like the above for the entire year or calendar pages for your time zone.

Sun and Moon Rising and Setting Events

LU                  Ephemeris of Sky Events for Interlochen/TC
September, 2021    Local time zone: EDT
+-----------------------------------------------------------------------+
| DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
|      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
+=======================================================================+
|Wed  1| 07:05a  08:18p  13:13 | 09:25p  05:59a |      Rise 01:57a   25%|
|Thu  2| 07:06a  08:17p  13:10 | 09:23p  06:00a |      Rise 02:55a   17%|
|Fri  3| 07:07a  08:15p  13:07 | 09:21p  06:01a |      Rise 04:01a   10%|
|Sat  4| 07:09a  08:13p  13:04 | 09:18p  06:03a |      Rise 05:11a    5%|
+------+-----------------------+----------------+-----------------------+
|Sun  5| 07:10a  08:11p  13:01 | 09:16p  06:04a |      Rise 06:24a    1%|
|Mon  6| 07:11a  08:09p  12:58 | 09:14p  06:06a |New   Set  08:30p    0%|
|Tue  7| 07:12a  08:07p  12:55 | 09:12p  06:07a |      Set  08:53p    1%|
|Wed  8| 07:13a  08:06p  12:52 | 09:10p  06:08a |      Set  09:16p    5%|
|Thu  9| 07:14a  08:04p  12:49 | 09:08p  06:10a |      Set  09:40p   11%|
|Fri 10| 07:16a  08:02p  12:46 | 09:06p  06:11a |      Set  10:05p   19%|
|Sat 11| 07:17a  08:00p  12:43 | 09:04p  06:12a |      Set  10:35p   29%|
+------+-----------------------+----------------+-----------------------+
|Sun 12| 07:18a  07:58p  12:40 | 09:02p  06:13a |      Set  11:12p   40%|
|Mon 13| 07:19a  07:56p  12:37 | 09:00p  06:15a |F Qtr Set  11:57p   52%|
|Tue 14| 07:20a  07:54p  12:33 | 08:58p  06:16a |      Set  12:53a   63%|
|Wed 15| 07:21a  07:52p  12:30 | 08:56p  06:17a |      Set  01:59a   73%|
|Thu 16| 07:23a  07:51p  12:27 | 08:54p  06:19a |      Set  03:10a   82%|
|Fri 17| 07:24a  07:49p  12:24 | 08:52p  06:20a |      Set  04:24a   90%|
|Sat 18| 07:25a  07:47p  12:21 | 08:50p  06:21a |      Set  05:37a   95%|
+------+-----------------------+----------------+-----------------------+
|Sun 19| 07:26a  07:45p  12:18 | 08:48p  06:23a |      Set  06:47a   99%|
|Mon 20| 07:27a  07:43p  12:15 | 08:46p  06:24a |Full  Rise 08:03p  100%|
|Tue 21| 07:29a  07:41p  12:12 | 08:44p  06:25a |      Rise 08:23p   99%|
|Wed 22| 07:30a  07:39p  12:09 | 08:42p  06:26a |      Rise 08:43p   96%|
|Thu 23| 07:31a  07:37p  12:06 | 08:40p  06:28a |      Rise 09:03p   91%|
|Fri 24| 07:32a  07:35p  12:03 | 08:39p  06:29a |      Rise 09:26p   85%|
|Sat 25| 07:33a  07:33p  12:00 | 08:37p  06:30a |      Rise 09:52p   78%|
+------+-----------------------+----------------+-----------------------+
|Sun 26| 07:35a  07:32p  11:57 | 08:35p  06:31a |      Rise 10:23p   69%|
|Mon 27| 07:36a  07:30p  11:53 | 08:33p  06:33a |      Rise 11:00p   60%|
|Tue 28| 07:37a  07:28p  11:50 | 08:31p  06:34a |L Qtr Rise 11:46p   51%|
|Wed 29| 07:38a  07:26p  11:47 | 08:29p  06:35a |      Rise 12:40a   41%|
|Thu 30| 07:39a  07:24p  11:44 | 08:27p  06:36a |      Rise 01:42a   32%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunrise and sunset
Generated using my LookingUp for DOS program.

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