Bob Moler's Ephemeris Blog

This is Ephemeris for Monday, the first of May. Today the Sun will be up for 14 hours and 14 minutes, setting at 8:47, and it will rise tomorrow at 6:31. The Moon, halfway from first quarter to full, will set at 5:20 tomorrow morning.

Let’s look ahead at the month of May, the month when the promise of spring is finally fulfilled. Daylight hours in the Interlochen/Traverse City area will increase from 14 hours and 14 minutes today to 15 hours 19 minutes on the 31st. The altitude, or angle, of the Sun above the southern horizon at local noon will ascend from 60 degrees today to 67 degrees at month’s end. The altitude of the Sun in the Straits area will be a degree lower than that. Local apparent noon this month, when the Sun passes due south, will be about 1:38 p.m. Early this month we’ll have The Eta Aquariid meteor shower early in the morning, though it will be hindered by a bright Moon. Venus and Mars are our evening planets. Venus will continue to approach Mars all month.

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

Addendum

May Evening Star Chart

Star Chart for May 2023 (11 p.m. EDT, May 15, 2023). Click or tap on image to enlarge it. Created using my LookingUp program.

The planets and stars are plotted for the 15th at 11 p.m. EDT in the evening and 4 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 of 11 p.m. and 4 a.m. 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 or 28 minutes. The planet positions are updated each Wednesday on this blog. For planet positions on dates other than the 15th, check the Wednesday planet posts on this blog for weekly positions.

May Morning Star Chart

Star Chart for May mornings, 2023 (4 a.m. EDT, May 15, 2023). Click or tap on 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, and
• Extend like a spike to Spica,
• EaqR is the radiant of the Eta Aquariid meteor shower that peaks on the 5th.

Twilight Limits, Nautical and Astronomical

The twilight calendar was generated using Cartes du Ciel (Sky Charts), with some corrections.

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

LU              Ephemeris of Sky Events for Interlochen/TC
May 2023    Local time zone: EDT
+-----------------------------------------------------------------------+
| DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
|      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
+=======================================================================+
|Mon  1| 06:33a  08:47p  14:14 | 09:59p  05:21a |      Set  05:20a   86%|
|Tue  2| 06:31a  08:48p  14:17 | 10:01p  05:19a |      Set  05:37a   92%|
|Wed  3| 06:30a  08:49p  14:19 | 10:02p  05:17a |      Set  05:56a   97%|
|Thu  4| 06:28a  08:51p  14:22 | 10:04p  05:15a |      Set  06:18a   99%|
|Fri  5| 06:27a  08:52p  14:25 | 10:06p  05:14a |Full  Rise 09:13p  100%|
|Sat  6| 06:25a  08:53p  14:27 | 10:07p  05:12a |      Rise 10:31p   98%|
+------+-----------------------+----------------+-----------------------+
|Sun  7| 06:24a  08:54p  14:30 | 10:09p  05:10a |      Rise 11:47p   94%|
|Mon  8| 06:23a  08:56p  14:32 | 10:10p  05:08a |      Rise 12:57a   87%|
|Tue  9| 06:22a  08:57p  14:35 | 10:12p  05:07a |      Rise 01:56a   78%|
|Wed 10| 06:20a  08:58p  14:37 | 10:13p  05:05a |      Rise 02:42a   68%|
|Thu 11| 06:19a  08:59p  14:40 | 10:15p  05:04a |      Rise 03:17a   57%|
|Fri 12| 06:18a  09:00p  14:42 | 10:16p  05:02a |L Qtr Rise 03:44a   45%|
|Sat 13| 06:17a  09:01p  14:44 | 10:18p  05:00a |      Rise 04:07a   34%|
+------+-----------------------+----------------+-----------------------+
|Sun 14| 06:15a  09:03p  14:47 | 10:19p  04:59a |      Rise 04:28a   24%|
|Mon 15| 06:14a  09:04p  14:49 | 10:21p  04:57a |      Rise 04:47a   15%|
|Tue 16| 06:13a  09:05p  14:51 | 10:23p  04:56a |      Rise 05:08a    8%|
|Wed 17| 06:12a  09:06p  14:53 | 10:24p  04:54a |      Rise 05:30a    3%|
|Thu 18| 06:11a  09:07p  14:55 | 10:25p  04:53a |      Rise 05:56a    1%|
|Fri 19| 06:10a  09:08p  14:58 | 10:27p  04:52a |New   Set  09:38p    0%|
|Sat 20| 06:09a  09:09p  15:00 | 10:28p  04:50a |      Set  10:48p    2%|
+------+-----------------------+----------------+-----------------------+
|Sun 21| 06:08a  09:10p  15:02 | 10:30p  04:49a |      Set  11:50p    6%|
|Mon 22| 06:07a  09:11p  15:04 | 10:31p  04:48a |      Set  12:43a   11%|
|Tue 23| 06:06a  09:12p  15:05 | 10:33p  04:46a |      Set  01:25a   18%|
|Wed 24| 06:06a  09:13p  15:07 | 10:34p  04:45a |      Set  01:59a   26%|
|Thu 25| 06:05a  09:14p  15:09 | 10:35p  04:44a |      Set  02:26a   35%|
|Fri 26| 06:04a  09:15p  15:11 | 10:37p  04:43a |      Set  02:48a   44%|
|Sat 27| 06:03a  09:16p  15:13 | 10:38p  04:42a |F Qtr Set  03:07a   53%|
+------+-----------------------+----------------+-----------------------+
|Sun 28| 06:02a  09:17p  15:14 | 10:39p  04:41a |      Set  03:24a   63%|
|Mon 29| 06:02a  09:18p  15:16 | 10:40p  04:40a |      Set  03:41a   72%|
|Tue 30| 06:01a  09:19p  15:17 | 10:42p  04:39a |      Set  03:59a   81%|
|Wed 31| 06:01a  09:20p  15:19 | 10:43p  04:38a |      Set  04:19a   88%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunset and the next
   sunrise