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07/30/2021 – Ephemeris – Previewing August skies

July 30, 2021 Comments off

This is Bob Moler with Ephemeris for Friday, July 30th. Today the Sun will be up for 14 hours and 43 minutes, setting at 9:10, and it will rise tomorrow at 6:28. The Moon, 1 day before last quarter, will rise at 12:38 tomorrow morning.

Let’s look ahead at the month of August in the skies. Daylight hours will decrease from 14 hours and 38 minutes on the 1st to 13 hours 16 minutes on the 31st. The altitude of the Sun at local noon, that is, degrees of angle above the horizon, will decrease from 63 degrees Sunday to just over 53 degrees on the 31st. Straits area listeners can subtract one more degree from those angles, but their daylight hours will be a few minutes longer. Local noon, when the Sun is due south, is about 1:43 p.m. The Perseid meteor shower will reach its peak at between 3 and 6 p.m. on the 12th. That means that more than likely the early mornings of the 12th and 13th will be equally good for viewing them. I tend to prefer viewing before the peak, if given a choice.

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

August Evening Star Chart

August evening star chart

Star Chart for August 2020 (10 pm EDT, August 15, 2021). Click on 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 5 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.

Note the chart times are for the 15th. For each week before the 15th, add ½ hour (28 minutes if you’re picky). For each week after the 15th, subtract ½ hour. The planet positions are updated each Wednesday on this blog. For planet positions on dates other than the 15th.

August Morning Star Chart

StarChart August Morning

Star Chart for August mornings, (5 a.m. EDT, August 15, 2021). Click on image to enlarge. 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, and
  • Extend like a spike to Spica.
  • The Summer Triangle is in red.
  • PerR is the radiant of the Perseid meteor shower (Peaks on the 12th)

Twilight Limits, Nautical and Astronomical

      EDT        
  Morning Twilight Evening Twilight Dark Night Moon
Date Astro. Nautical Nautical Astro. Start End Illum.
2021-08-01 4h31m 5h19m 22h26m 23h15m 23h15m 1h00m 0.35
2021-08-02 4h32m 5h20m 22h25m 23h13m 23h13m 1h25m 0.26
2021-08-03 4h34m 5h22m 22h23m 23h11m 23h11m 1h55m 0.18
2021-08-04 4h36m 5h23m 22h21m 23h08m 23h08m 2h31m 0.11
2021-08-05 4h38m 5h25m 22h20m 23h06m 23h06m 3h16m 0.06
2021-08-06 4h40m 5h26m 22h18m 23h04m 23h04m 4h09m 0.02
2021-08-07 4h42m 5h28m 22h16m 23h02m 23h02m 4h42m 0
2021-08-08 4h44m 5h29m 22h14m 23h00m 23h00m 4h44m 0
2021-08-09 4h46m 5h31m 22h13m 22h58m 22h58m 4h46m 0.03
2021-08-10 4h48m 5h32m 22h11m 22h55m 22h55m 4h48m 0.08
2021-08-11 4h50m 5h34m 22h09m 22h53m 22h53m 4h50m 0.15
2021-08-12 4h51m 5h35m 22h07m 22h51m 23h13m 4h51m 0.24
2021-08-13 4h53m 5h37m 22h05m 22h49m 23h36m 4h53m 0.34
2021-08-14 4h55m 5h38m 22h03m 22h47m – 4h55m 0.45
2021-08-15 4h57m 5h40m 22h02m 22h44m 0h03m 4h57m 0.57
2021-08-16 4h59m 5h41m 22h00m 22h42m 0h34m 4h59m 0.68
2021-08-17 5h01m 5h43m 21h58m 22h40m 1h13m 5h01m 0.78
2021-08-18 5h02m 5h44m 21h56m 22h38m 2h02m 5h02m 0.87
2021-08-19 5h04m 5h46m 21h54m 22h36m 3h02m 5h04m 0.94
2021-08-20 5h06m 5h47m 21h52m 22h33m 4h12m 5h06m 0.98
2021-08-21 5h08m 5h49m 21h50m 22h31m – – 1
2021-08-22 5h09m 5h50m 21h48m 22h29m – – 0.99
2021-08-23 5h11m 5h52m 21h46m 22h27m – – 0.97
2021-08-24 5h13m 5h53m 21h44m 22h24m – – 0.92
2021-08-25 5h15m 5h54m 21h42m 22h22m – – 0.86
2021-08-26 5h16m 5h56m 21h40m 22h20m 22h20m 22h40m 0.78
2021-08-27 5h18m 5h57m 21h38m 22h18m 22h18m 23h01m 0.69
2021-08-28 5h20m 5h59m 21h36m 22h15m 22h15m 23h25m 0.6
2021-08-29 5h21m 6h00m 21h34m 22h13m 22h13m 23h53m 0.51
2021-08-30 5h23m 6h01m 21h32m 22h11m 22h11m – 0.42
2021-08-31 5h24m 6h03m 21h30m 22h09m 22h09m 0h26m 0.32

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

    Date     Time    Event
Aug  1  Su            Venus: 33.1° E
     1  Su  10:00 am  Mercury Superior Conj.
     2  Mo   1:24 am  Saturn Opposition
     2  Mo   3:35 am  Moon Apogee: 404400 km
     2  Mo  10:51 pm  Moon Ascending Node
     5  Th  12:46 pm  Moon North Dec.: 25.7° N
     8  Su   9:50 am  New Moon
    11  We   3:00 am  Moon-Venus: 4.4° S
    12  Th   3:11 pm  Perseid Shower: ZHR = 90
    15  Su  11:20 am  First Quarter
    16  Mo  12:04 pm  Moon Descending Node
    17  Tu   5:23 am  Moon Perigee: 369100 km
    18  We   6:24 pm  Moon South Dec.: 25.8° S
    18  We  11:03 pm  Mercury-Mars: 0.1° N
    19  Th   7:05 pm  Jupiter Opposition
    20  Fr   6:19 pm  Moon-Saturn: 3.8° N
    22  Su  12:52 am  Moon-Jupiter: 4.1° N
    22  Su   8:02 am  Full Moon
    29  Su  10:22 pm  Moon Apogee: 404100 km
    30  Mo   1:13 am  Moon Ascending Node
    30  Mo   3:13 am  Last Quarter
Sep  1  We            Venus: 39.9° E

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

                  Ephemeris of Sky Events for Interlochen/TC
August, 2021    Local time zone: EDT
+-----------------------------------------------------------------------+
| DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
|      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
+=======================================================================+
|Sun  1| 06:29a  09:08p  14:38 | 10:23p  05:13a |      Rise 01:25a   36%|
|Mon  2| 06:30a  09:06p  14:36 | 10:21p  05:15a |      Rise 01:55a   28%|
|Tue  3| 06:31a  09:05p  14:33 | 10:20p  05:16a |      Rise 02:31a   20%|
|Wed  4| 06:32a  09:04p  14:31 | 10:18p  05:18a |      Rise 03:16a   13%|
|Thu  5| 06:33a  09:02p  14:29 | 10:16p  05:19a |      Rise 04:09a    7%|
|Fri  6| 06:35a  09:01p  14:26 | 10:14p  05:21a |      Rise 05:11a    3%|
|Sat  7| 06:36a  09:00p  14:23 | 10:13p  05:22a |      Rise 06:18a    1%|
+------+-----------------------+----------------+-----------------------+
|Sun  8| 06:37a  08:58p  14:21 | 10:11p  05:24a |New   Set  09:35p    0%|
|Mon  9| 06:38a  08:57p  14:18 | 10:09p  05:25a |      Set  10:03p    2%|
|Tue 10| 06:39a  08:55p  14:16 | 10:07p  05:27a |      Set  10:27p    7%|
|Wed 11| 06:40a  08:54p  14:13 | 10:05p  05:28a |      Set  10:50p   13%|
|Thu 12| 06:42a  08:52p  14:10 | 10:04p  05:30a |      Set  11:13p   22%|
|Fri 13| 06:43a  08:51p  14:08 | 10:02p  05:31a |      Set  11:36p   32%|
|Sat 14| 06:44a  08:49p  14:05 | 10:00p  05:33a |      Set  12:03a   43%|
+------+-----------------------+----------------+-----------------------+
|Sun 15| 06:45a  08:48p  14:02 | 09:58p  05:34a |F Qtr Set  12:34a   54%|
|Mon 16| 06:46a  08:46p  13:59 | 09:56p  05:36a |      Set  01:13a   65%|
|Tue 17| 06:47a  08:44p  13:56 | 09:54p  05:37a |      Set  02:02a   76%|
|Wed 18| 06:49a  08:43p  13:54 | 09:52p  05:39a |      Set  03:02a   85%|
|Thu 19| 06:50a  08:41p  13:51 | 09:50p  05:40a |      Set  04:11a   92%|
|Fri 20| 06:51a  08:39p  13:48 | 09:48p  05:42a |      Set  05:26a   97%|
|Sat 21| 06:52a  08:38p  13:45 | 09:46p  05:43a |      Set  06:40a  100%|
+------+-----------------------+----------------+-----------------------+
|Sun 22| 06:53a  08:36p  13:42 | 09:45p  05:44a |Full  Rise 09:15p  100%|
|Mon 23| 06:54a  08:34p  13:39 | 09:43p  05:46a |      Rise 09:39p   97%|
|Tue 24| 06:56a  08:33p  13:36 | 09:41p  05:47a |      Rise 10:00p   93%|
|Wed 25| 06:57a  08:31p  13:34 | 09:39p  05:49a |      Rise 10:20p   87%|
|Thu 26| 06:58a  08:29p  13:31 | 09:37p  05:50a |      Rise 10:40p   79%|
|Fri 27| 06:59a  08:27p  13:28 | 09:35p  05:52a |      Rise 11:01p   71%|
|Sat 28| 07:00a  08:26p  13:25 | 09:33p  05:53a |      Rise 11:25p   62%|
+------+-----------------------+----------------+-----------------------+
|Sun 29| 07:02a  08:24p  13:22 | 09:31p  05:54a |      Rise 11:53p   53%|
|Mon 30| 07:03a  08:22p  13:19 | 09:29p  05:56a |L Qtr Rise 12:26a   43%|
|Tue 31| 07:04a  08:20p  13:16 | 09:27p  05:57a |      Rise 01:07a   34%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunrise and sunset

Generated using my LookingUp for DOS program.

Categories: Ephemeris Program, Month preview Tags: