Bob Moler's Ephemeris Blog

This is Ephemeris for Monday, December 1st. Today the Sun will be up for 9 hours and 3 minutes, setting at 5:03, and it will rise tomorrow at 8:01. The Moon, halfway from first quarter to full, will set at 5:06 tomorrow morning.

Let’s look ahead at the skies of December. We are now in the holiday season and about to celebrate the southernmost travel of the Sun in the sky and its return northward. The Sun will stop its travel south, the winter solstice on the 21st at 10:03 a.m. That will make that day the shortest day in terms of daylight hours. However, the earliest sunset and latest sunrise don’t coincide with that date. The earliest sunset it will be on the 9th just one minute earlier than today. The latest sunrise will be just a couple of days into next year. The reason is the Earth is closer to the Sun than average and is moving faster in its orbit than it normally does. It skews the sunrise and sunset times.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.

Addendum

December Evening Star Chart

The planets and stars are plotted for the 15th at 9 pm EST 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).

December Morning Star Chart

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.
• The leaky bowl of the Big Dipper drips on Leo.
• Follow the arc of the handle of the Big Dipper to the star Arcturus, then
• Follow the spike to Spica.
• The Summer Triangle is in red.
• GemR on the star charts is the radiant of the Geminid meteor shower, which peaks on the morning of the 14th.

Twilight Limits, Nautical and Astronomical

			EST
	Morning	Twilight	Evening	Twilight	Dark	Night	Moon
Date	Astro.	Nautical	Nautical	Astro.	Start	End	Illum.
2025-12-01	6h17m	6h52m	18h12m	18h47m	3h45m	6h17m	0.89
2025-12-02	6h18m	6h53m	18h12m	18h47m	5h07m	6h18m	0.95
2025-12-03	6h19m	6h54m	18h12m	18h47m	–	–	0.99
2025-12-04	6h20m	6h55m	18h11m	18h47m	–	–	1.00
2025-12-05	6h20m	6h56m	18h11m	18h47m	–	–	0.98
2025-12-06	6h21m	6h57m	18h11m	18h47m	–	–	0.93
2025-12-07	6h22m	6h57m	18h11m	18h47m	18h47m	19h59m	0.86
2025-12-08	6h23m	6h58m	18h11m	18h47m	18h47m	21h19m	0.77
2025-12-09	6h24m	6h59m	18h11m	18h47m	18h47m	22h35m	0.67
2025-12-10	6h25m	7h00m	18h11m	18h47m	18h47m	23h46m	0.57
2025-12-11	6h25m	7h01m	18h11m	18h47m	18h47m	–	0.47
2025-12-12	6h26m	7h02m	18h12m	18h47m	18h47m	0h53m	0.37
2025-12-13	6h27m	7h02m	18h12m	18h47m	18h47m	1h59m	0.28
2025-12-14	6h28m	7h03m	18h12m	18h48m	18h48m	3h03m	0.20
2025-12-15	6h28m	7h04m	18h12m	18h48m	18h48m	4h08m	0.13
2025-12-16	6h29m	7h04m	18h13m	18h48m	18h48m	5h14m	0.07
2025-12-17	6h30m	7h05m	18h13m	18h48m	18h48m	6h20m	0.03
2025-12-18	6h30m	7h06m	18h13m	18h49m	18h49m	6h30m	0.01
2025-12-19	6h31m	7h06m	18h14m	18h49m	18h49m	6h31m	0.00
2025-12-20	6h31m	7h07m	18h14m	18h50m	18h50m	6h31m	0.01
2025-12-21	6h32m	7h07m	18h15m	18h50m	18h50m	6h32m	0.04
2025-12-22	6h32m	7h08m	18h15m	18h51m	19h31m	6h32m	0.09
2025-12-23	6h33m	7h08m	18h16m	18h51m	20h41m	6h33m	0.16
2025-12-24	6h33m	7h09m	18h16m	18h52m	21h51m	6h33m	0.24
2025-12-25	6h33m	7h09m	18h17m	18h52m	23h02m	6h33m	0.33
2025-12-26	6h34m	7h09m	18h18m	18h53m	–	6h34m	0.44
2025-12-27	6h34m	7h10m	18h18m	18h54m	0h13m	6h34m	0.55
2025-12-28	6h34m	7h10m	18h19m	18h54m	1h27m	6h34m	0.66
2025-12-29	6h35m	7h10m	18h20m	18h55m	2h44m	6h35m	0.76
2025-12-30	6h35m	7h10m	18h20m	18h56m	4h05m	6h35m	0.86
2025-12-31	6h35m	7h10m	18h21m	19h01m	5h28m	6h35m	0.93
2026-01-01	6h35m	7h11m	18h22m	19h01m	–	–	0.98

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

Dec  1  Mo            Venus: 8.7° W
     3  We   9:54 PM  Moon-Pleiades: 0.8° S
     4  Th   6:06 AM  Moon Perigee: 357000 km
     4  Th   6:14 PM  Full Moon
     5  Fr   4:51 PM  Moon North Dec.: 28.3° N
     7  Su  10:48 AM  Moon-Jupiter: 3.7° S
     7  Su  11:21 AM  Moon-Pollux: 2.9° N
     7  Su   3:59 PM  Mercury Elongation: 20.7° W
     8  Mo   9:23 AM  Moon-Beehive: 1.5° S
    10  We   1:32 AM  Moon-Regulus: 0.8° S
    11  Th   2:34 AM  Moon Descending Node
    11  Th   3:52 PM  Last Quarter
    14  Su   2:21 AM  Geminid Shower: ZHR = 120
    14  Su  11:27 AM  Moon-Spica: 1.5° N
    17  We   1:09 AM  Moon Apogee: 406300 km
    17  We   3:41 PM  Jupiter-Pollux: 6.5° S
    19  Fr   9:07 AM  Mercury-Antares: 5.5° N
    19  Fr   6:18 PM  Moon South Dec.: 28.2° S
    19  Fr   8:43 PM  New Moon
    21  Su  10:03 AM  Winter Solstice
    22  Mo  11:00 AM  Ursid Shower: ZHR = 10
    25  Th   5:03 PM  Moon Ascending Node
    26  Fr  10:24 PM  Moon-Saturn: 4.2° S
    27  Sa   2:10 PM  First Quarter
    31  We   8:21 AM  Moon-Pleiades: 0.9° S

All event times are given for UTC-5, Eastern Standard 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.

Note that the site is now kept up for archival purposes. Fred Espenak retired from NASA several years ago and has recently passed away. His own site, AstroPixels, which is still up, contains much the same information: http://astropixels.com/almanac/almanac.html. However, it uses standard time all year.

Sun and Moon Rising and Setting Times

LU              Ephemeris of Sky Events for Interlochen/TC
December, 2025    Local time zone: EST
+-----------------------------------------------------------------------+
| DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
|      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
+=======================================================================+
|Mon  1| 08:00a  05:03p  09:03 | 06:12p  06:50a |      Set  05:06a   87%|
|Tue  2| 08:01a  05:03p  09:01 | 06:12p  06:51a |      Set  06:32a   94%|
|Wed  3| 08:02a  05:02p  09:00 | 06:12p  06:52a |      Set  07:59a   98%|
|Thu  4| 08:03a  05:02p  08:59 | 06:12p  06:53a |Full  Rise 04:24p  100%|
|Fri  5| 08:04a  05:02p  08:57 | 06:12p  06:54a |      Rise 05:25p   98%|
|Sat  6| 08:05a  05:02p  08:56 | 06:12p  06:55a |      Rise 06:39p   94%|
+------+-----------------------+----------------+-----------------------+
|Sun  7| 08:06a  05:02p  08:55 | 06:12p  06:56a |      Rise 07:59p   87%|
|Mon  8| 08:07a  05:02p  08:54 | 06:12p  06:57a |      Rise 09:19p   78%|
|Tue  9| 08:08a  05:02p  08:53 | 06:12p  06:58a |      Rise 10:34p   69%|
|Wed 10| 08:09a  05:02p  08:52 | 06:12p  06:59a |      Rise 11:45p   59%|
|Thu 11| 08:10a  05:02p  08:51 | 06:12p  06:59a |L Qtr Rise 12:53a   49%|
|Fri 12| 08:11a  05:02p  08:51 | 06:12p  07:00a |      Rise 01:58a   39%|
|Sat 13| 08:11a  05:02p  08:50 | 06:12p  07:01a |      Rise 03:03a   30%|
+------+-----------------------+----------------+-----------------------+
|Sun 14| 08:12a  05:02p  08:49 | 06:13p  07:02a |      Rise 04:08a   22%|
|Mon 15| 08:13a  05:02p  08:49 | 06:13p  07:02a |      Rise 05:13a   14%|
|Tue 16| 08:14a  05:03p  08:49 | 06:13p  07:03a |      Rise 06:19a    8%|
|Wed 17| 08:14a  05:03p  08:48 | 06:14p  07:04a |      Rise 07:23a    4%|
|Thu 18| 08:15a  05:03p  08:48 | 06:14p  07:04a |      Rise 08:22a    1%|
|Fri 19| 08:16a  05:04p  08:48 | 06:14p  07:05a |New   Set  04:21p    0%|
|Sat 20| 08:16a  05:04p  08:48 | 06:15p  07:05a |      Set  05:18p    1%|
+------+-----------------------+----------------+-----------------------+
|Sun 21| 08:17a  05:05p  08:48 | 06:15p  07:06a |      Set  06:22p    4%|
|Mon 22| 08:17a  05:05p  08:48 | 06:16p  07:06a |      Set  07:30p    8%|
|Tue 23| 08:18a  05:06p  08:48 | 06:17p  07:07a |      Set  08:40p   14%|
|Wed 24| 08:18a  05:06p  08:48 | 06:17p  07:07a |      Set  09:51p   22%|
|Thu 25| 08:18a  05:07p  08:48 | 06:18p  07:08a |      Set  11:01p   31%|
|Fri 26| 08:19a  05:08p  08:49 | 06:18p  07:08a |      Set  12:13a   41%|
|Sat 27| 08:19a  05:08p  08:49 | 06:19p  07:08a |F Qtr Set  01:26a   52%|
+------+-----------------------+----------------+-----------------------+
|Sun 28| 08:19a  05:09p  08:50 | 06:20p  07:09a |      Set  02:43a   63%|
|Mon 29| 08:19a  05:10p  08:50 | 06:21p  07:09a |      Set  04:04a   74%|
|Tue 30| 08:19a  05:11p  08:51 | 06:21p  07:09a |      Set  05:28a   84%|
|Wed 31| 08:20a  05:12p  08:52 | 06:22p  07:09a |      Set  06:49a   91%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunset and sunrise

Generated using my LookingUp for DOS program.