Bob Moler's Ephemeris Blog

This is Ephemeris for Friday, July 31st. Today the Sun will be up for 14 hours and 41 minutes, setting at 9:09, and it will rise tomorrow at 6:29. The Moon, 2 days past full, will rise at 10:12 this evening.

Let’s look ahead at the month of August in the skies. Daylight hours will decrease from 14 hours and 39 minutes tomorrow to 13 hours 17 minutes on the 31st. The altitude of the Sun at local noon, that is degrees of angle above the southern horizon, will decrease from 63 degrees tomorrow to just over 53 degrees on the 31st. Straits area listeners can subtract one more degree from those angles. Local noon, when the Sun is due south, is about 1:43 p.m. During August we have 3 astronomical events occurring. The first is August 12th, a double header: during the day a little nibble of a solar eclipse and in the evening the peak of the Perseid meteor shower, generally the best of the year, for us. And late night on the 27th we have an eclipse of the Moon that will be almost total.

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

August Evening Star Chart

The planets and stars are plotted for the 15th at 10 PM EDT in the evening and 4:30 AM on the 16th for the morning chart. These are the chart times. Note that Interlochen/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.
Note, the chart times of 10 PM and 4:30 AM are for the 15th & 16th respectively. For each week before these dates, add ½ hour (28 minutes if you’re picky). For each week after the 15th, subtract ½ hour, or 28 minutes. The planet positions are updated each Wednesday on this blog.

August Morning Star Chart

Twilight Limits, Nautical and Astronomical

			EDT
	Morning	Twilight	Evening	Twilight	Dark	Night	Moon
Date	Astro.	Nautical	Nautical	Astro.	Start	End	Illum.
2026-08-01	4h27m	5h15m	22h27m	23h15m	–	–	87%
2026-08-02	4h29m	5h17m	22h25m	23h13m	–	–	80%
2026-08-03	4h31m	5h18m	22h24m	23h11m	–	–	70%
2026-08-04	4h33m	5h20m	22h22m	23h09m	23h09m	23h30m	60%
2026-08-05	4h35m	5h21m	22h20m	23h07m	23h07m	23h57m	49%
2026-08-06	4h36m	5h23m	22h18m	23h05m	23h05m	–	38%
2026-08-07	4h38m	5h24m	22h17m	23h02m	23h02m	0h33m	27%
2026-08-08	4h40m	5h26m	22h15m	23h00m	23h00m	1h20m	17%
2026-08-09	4h42m	5h27m	22h13m	22h58m	22h58m	2h22m	9%
2026-08-10	4h44m	5h29m	22h11m	22h56m	22h56m	3h36m	3%
2026-08-11	4h46m	5h30m	22h10m	22h54m	22h54m	4h46m	0%
2026-08-12	4h48m	5h32m	22h08m	22h52m	22h52m	4h48m	0%
2026-08-13	4h50m	5h33m	22h06m	22h49m	22h49m	4h50m	3%
2026-08-14	4h51m	5h35m	22h04m	22h47m	22h47m	4h51m	8%
2026-08-15	4h53m	5h36m	22h02m	22h45m	22h45m	4h53m	15%
2026-08-16	4h55m	5h38m	22h00m	22h43m	22h43m	4h55m	23%
2026-08-17	4h57m	5h39m	21h58m	22h41m	22h42m	4h57m	32%
2026-08-18	4h59m	5h41m	21h56m	22h38m	23h06m	4h59m	41%
2026-08-19	5h00m	5h42m	21h55m	22h36m	23h35m	5h00m	51%
2026-08-20	5h02m	5h43m	21h53m	22h34m	–	5h02m	61%
2026-08-21	5h04m	5h45m	21h51m	22h32m	0h12m	5h04m	70%
2026-08-22	5h06m	5h46m	21h49m	22h29m	0h57m	5h06m	78%
2026-08-23	5h07m	5h48m	21h47m	22h27m	1h51m	5h07m	85%
2026-08-24	5h09m	5h49m	21h45m	22h25m	2h52m	5h09m	91%
2026-08-25	5h11m	5h51m	21h43m	22h23m	3h58m	5h11m	96%
2026-08-26	5h12m	5h52m	21h41m	22h20m	5h07m	5h12m	99%
2026-08-27	5h14m	5h53m	21h39m	22h18m	–	–	100%
2026-08-28	5h16m	5h55m	21h37m	22h16m	–	–	99%
2026-08-29	5h17m	5h56m	21h35m	22h14m	–	–	95%
2026-08-30	5h19m	5h58m	21h33m	22h11m	–	–	90%
2026-08-31	5h21m	5h59m	21h31m	22h09m	–	–	82%

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

Aug  1  Sa            Venus: 45.3° E
     2  Su   3:59 AM  Mercury Elongation: 19.5° W
     5  We  10:21 PM  Last Quarter
     7  Fr   2:23 AM  Moon-Pleiades: 1.2° S
     8  Sa   7:42 PM  Moon North Dec.: 28.1° N
     9  Su   1:31 AM  Moon-Mars: 4.4° S
    10  Mo   7:18 AM  Moon Perigee: 363300 km
    12  We   1:37 PM  New Moon
    12  We   1:47 PM  Total Solar Eclipse
                      11% Partial Solar Eclipse in N. Michigsn
    12  We   9:56 PM  Perseid Shower: ZHR = 90
    13  Th   5:56 AM  Moon Descending Node
    15  Sa   1:59 AM  Venus Elongation: 45.9° E
    16  Su   4:46 AM  Moon-Venus: 2.2° N
    17  Mo   7:49 AM  Moon-Spica: 2.6° N
    19  We  10:46 PM  First Quarter
    21  Fr  12:17 AM  Moon-Antares: 0.7° N
    22  Sa   4:20 AM  Moon Apogee: 404600 km
    22  Sa   6:59 AM  Moon South Dec.: 28.1° S
    27  Th  12:44 PM  Mercury Superior Conjunction
    27  Th   2:47 PM  Moon Ascending Node
    28  Fr  12:14 AM  Partial Lunar Eclipse
    28  Fr  12:18 AM  Full Moon
Sep  1  Tu            Venus: 44.6° E

All event times are given for UTC-4:00 Eastern Daylight Saving Time.

Events in bold will be covered in subsequent posts on this blog. Also, the August 2026 issue of the Grand Traverse Astronomical Society’s Stellar Sentinel contains an article I wrote about them. Access it here when it is published in a few days.

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 his own site, AstroPixels, which contain the same information: http://astropixels.com/almanac/almanac.html. However, it uses standard time all year.

Fred passed away a year ago, on June 1, 2025. RIP.

Sun and Moon Rising and Setting Events

LU          Ephemeris of Sky Events for Interlochen/TC
August, 2026    Local time zone: EDT
+-----------------------------------------------------------------------+
| DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
|      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
+=======================================================================+
|Sat  1| 06:29a  09:08p  14:39 | 10:23p  05:13a |      Rise 10:30p   89%|
+------+-----------------------+----------------+-----------------------+
|Sun  2| 06:30a  09:07p  14:36 | 10:22p  05:14a |      Rise 10:48p   81%|
|Mon  3| 06:31a  09:05p  14:34 | 10:20p  05:16a |      Rise 11:07p   72%|
|Tue  4| 06:32a  09:04p  14:32 | 10:18p  05:17a |      Rise 11:29p   62%|
|Wed  5| 06:33a  09:03p  14:29 | 10:17p  05:19a |L Qtr Rise 11:57p   51%|
|Thu  6| 06:34a  09:01p  14:26 | 10:15p  05:20a |      Rise 12:32a   40%|
|Fri  7| 06:35a  09:00p  14:24 | 10:13p  05:22a |      Rise 01:20a   29%|
|Sat  8| 06:37a  08:58p  14:21 | 10:11p  05:23a |      Rise 02:21a   19%|
+------+-----------------------+----------------+-----------------------+
|Sun  9| 06:38a  08:57p  14:19 | 10:10p  05:25a |      Rise 03:36a   10%|
|Mon 10| 06:39a  08:56p  14:16 | 10:08p  05:26a |      Rise 04:58a    4%|
|Tue 11| 06:40a  08:54p  14:13 | 10:06p  05:28a |      Rise 06:22a    1%|
|Wed 12| 06:41a  08:53p  14:11 | 10:04p  05:29a |New   Set  09:00p    0%|
|Thu 13| 06:42a  08:51p  14:08 | 10:02p  05:31a |      Set  09:22p    2%|
|Fri 14| 06:44a  08:49p  14:05 | 10:00p  05:32a |      Set  09:42p    7%|
|Sat 15| 06:45a  08:48p  14:03 | 09:58p  05:34a |      Set  10:01p   13%|
+------+-----------------------+----------------+-----------------------+
|Sun 16| 06:46a  08:46p  14:00 | 09:57p  05:35a |      Set  10:20p   21%|
|Mon 17| 06:47a  08:45p  13:57 | 09:55p  05:37a |      Set  10:41p   30%|
|Tue 18| 06:48a  08:43p  13:54 | 09:53p  05:38a |      Set  11:05p   39%|
|Wed 19| 06:50a  08:41p  13:51 | 09:51p  05:40a |F Qtr Set  11:35p   49%|
|Thu 20| 06:51a  08:40p  13:49 | 09:49p  05:41a |      Set  12:11a   58%|
|Fri 21| 06:52a  08:38p  13:46 | 09:47p  05:43a |      Set  12:56a   68%|
|Sat 22| 06:53a  08:36p  13:43 | 09:45p  05:44a |      Set  01:50a   76%|
+------+-----------------------+----------------+-----------------------+
|Sun 23| 06:54a  08:35p  13:40 | 09:43p  05:46a |      Set  02:51a   84%|
|Mon 24| 06:55a  08:33p  13:37 | 09:41p  05:47a |      Set  03:57a   90%|
|Tue 25| 06:57a  08:31p  13:34 | 09:39p  05:49a |      Set  05:06a   95%|
|Wed 26| 06:58a  08:30p  13:31 | 09:37p  05:50a |      Set  06:15a   99%|
|Thu 27| 06:59a  08:28p  13:28 | 09:35p  05:51a |      Set  07:25a  100%|
|Fri 28| 07:00a  08:26p  13:25 | 09:33p  05:53a |Full  Rise 08:36p   99%|
|Sat 29| 07:01a  08:24p  13:22 | 09:31p  05:54a |      Rise 08:54p   96%|
+------+-----------------------+----------------+-----------------------+
|Sun 30| 07:02a  08:22p  13:19 | 09:29p  05:56a |      Rise 09:14p   91%|
|Mon 31| 07:04a  08:21p  13:17 | 09:27p  05:57a |      Rise 09:35p   84%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunset and sunrise

Generated using my LookingUp for DOS app.