Archive
04/01/2021 – Ephemeris – Previewing April Skies
This is Bob Moler with Ephemeris for Wednesday, March 31st. Today the Sun will be up for 12 hours and 44 minutes, setting at 8:09, and it will rise tomorrow at 7:23. The Moon, 3 days past full, will rise at 12:11 tomorrow morning.
Let’s search for the naked-eye planets for this week. Unfortunately the only one you’ll find in the evening is Mars. It can be found in the west-southwest at 9 pm tonight, above the orange star Aldebaran in the face of Taurus the bull. Mars will set at 1:54 am. Right now three of the other four naked eye planets are just west of the Sun in the Morning sky. Venus is now below and just a bit east of the Sun, setting four minutes after sunset. Only Saturn and Jupiter are at a far enough angle from the Sun to be just spotted in the morning twilight. Saturn will rise at 5:10 am, with Jupiter rising 31 minutes later. By 6:30 am they will be low in the southeast. The Sun is rising earlier by 2 minutes a day now, while sunset is nearly matching that pace in the opposite direction.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
April Evening Star Chart
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. The brilliant planet Venus is our Evening Star in the West at chart time. Note that Traverse City is located approximately 45 minutes behind our time meridian, West 75° longitude. (An hour and 45 minutes behind our daylight saving time meridian during EDT).
April 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 appears in red.
- LyrR is the radiant of the Lyrid meteor shower which will reach peak on the morning of the 22nd.
- the 22nd.
Twilight Limits, Nautical and Astronomical
| Morning | Twilight | Evening | Twilight | Dark | Night | Moon | |
| Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
| 2021-04-01 | 5h46m | 6h23m | 21h18m | 21h54m | 21h54m | 0h11m | 0.74 |
| 2021-04-02 | 5h44m | 6h21m | 21h19m | 21h56m | 21h56m | 1h29m | 0.64 |
| 2021-04-03 | 5h42m | 6h19m | 21h20m | 21h57m | 21h57m | 2h42m | 0.52 |
| 2021-04-04 | 5h39m | 6h17m | 21h22m | 21h59m | 21h59m | 3h44m | 0.42 |
| 2021-04-05 | 5h37m | 6h15m | 21h23m | 22h01m | 22h01m | 4h35m | 0.31 |
| 2021-04-06 | 5h35m | 6h13m | 21h25m | 22h02m | 22h02m | 5h16m | 0.22 |
| 2021-04-07 | 5h33m | 6h11m | 21h26m | 22h04m | 22h04m | 5h33m | 0.14 |
| 2021-04-08 | 5h31m | 6h09m | 21h27m | 22h05m | 22h05m | 5h31m | 0.08 |
| 2021-04-09 | 5h28m | 6h07m | 21h29m | 22h07m | 22h07m | 5h28m | 0.03 |
| 2021-04-10 | 5h26m | 6h05m | 21h30m | 22h09m | 22h09m | 5h26m | 0.01 |
| 2021-04-11 | 5h24m | 6h03m | 21h32m | 22h10m | 22h10m | 5h24m | 0 |
| 2021-04-12 | 5h22m | 6h01m | 21h33m | 22h12m | 22h12m | 5h22m | 0.01 |
| 2021-04-13 | 5h20m | 5h59m | 21h35m | 22h14m | 22h14m | 5h20m | 0.04 |
| 2021-04-14 | 5h17m | 5h57m | 21h36m | 22h16m | 23h12m | 5h17m | 0.08 |
| 2021-04-15 | 5h15m | 5h55m | 21h38m | 22h17m | – | 5h15m | 0.14 |
| 2021-04-16 | 5h13m | 5h53m | 21h39m | 22h19m | 0h14m | 5h13m | 0.22 |
| 2021-04-17 | 5h11m | 5h51m | 21h41m | 22h21m | 1h15m | 5h11m | 0.3 |
| 2021-04-18 | 5h09m | 5h49m | 21h42m | 22h23m | 2h12m | 5h09m | 0.39 |
| 2021-04-19 | 5h06m | 5h47m | 21h44m | 22h24m | 3h03m | 5h06m | 0.49 |
| 2021-04-20 | 5h04m | 5h45m | 21h45m | 22h26m | 3h47m | 5h04m | 0.59 |
| 2021-04-21 | 5h02m | 5h43m | 21h47m | 22h28m | 4h25m | 5h02m | 0.7 |
| 2021-04-22 | 5h00m | 5h41m | 21h48m | 22h30m | 4h56m | 5h00m | 0.79 |
| 2021-04-23 | 4h57m | 5h39m | 21h50m | 22h32m | – | – | 0.88 |
| 2021-04-24 | 4h55m | 5h37m | 21h51m | 22h34m | – | – | 0.94 |
| 2021-04-25 | 4h53m | 5h35m | 21h53m | 22h35m | – | – | 0.99 |
| 2021-04-26 | 4h51m | 5h34m | 21h55m | 22h37m | – | – | 1 |
| 2021-04-27 | 4h49m | 5h32m | 21h56m | 22h39m | – | – | 0.98 |
| 2021-04-28 | 4h46m | 5h30m | 21h58m | 22h41m | 22h41m | 23h06m | 0.94 |
| 2021-04-29 | 4h44m | 5h28m | 21h59m | 22h43m | 22h43m | – | 0.87 |
| 2021-04-30 | 4h42m | 5h26m | 22h01m | 22h45m | 22h45m | 0h25m | 0.78 |
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
Apr 1 Th Venus: 2° E
1 Th 10:41 pm Moon Descending Node
3 Sa 10:08 pm Moon South Dec.: 25.4° S
4 Su 6:02 am Last Quarter
6 Tu 4:34 am Moon-Saturn: 4.2° N
7 We 3:15 am Moon-Jupiter: 4.7° N
11 Su 10:31 pm New Moon
14 We 1:47 pm Moon Apogee: 406100 km
16 Fr 1:53 am Moon Ascending Node
17 Sa 8:09 am Moon-Mars: 0.1° N,
Occultation Africa-Asia
18 Su 12:02 pm Moon North Dec.: 25.5° N
18 Su 9:31 pm Mercury Superior Conj.
20 Tu 2:59 am First Quarter
20 Tu 2:25 pm Moon-Beehive: 3° S
22 Th 8:16 am Lyrid Shower: ZHR = 20
26 Mo 11:31 pm Full Moon - Supermoon
27 Tu 11:24 am Moon Perigee: 357400 km
29 Th 5:17 am Moon Descending Node
30 Fr 5:15 pm Uranus Conjunction
May 1 Sa Venus: 9.4° E
Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC),
http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html.
Sun and Moon Rising and Setting Events
Ephemeris of Sky Events for Interlochen/TC
April, 2021 Local time zone: EDT
+-----------------------------------------------------------------------+
| DATE | SUN SUN DAYLIGHT| TWILIGHT* |MOON RISE OR ILLUM |
| | RISE SET HOURS | END START |PHASE SET** TIME FRACTN|
+=======================================================================+
|Thu 1| 07:23a 08:10p 12:47 | 09:15p 06:18a | Rise 01:29a 76%|
|Fri 2| 07:21a 08:12p 12:50 | 09:17p 06:16a | Rise 02:42a 66%|
|Sat 3| 07:19a 08:13p 12:53 | 09:18p 06:14a | Rise 03:44a 55%|
+------+-----------------------+----------------+-----------------------+
|Sun 4| 07:17a 08:14p 12:56 | 09:19p 06:12a |L Qtr Rise 04:35a 44%|
|Mon 5| 07:15a 08:15p 13:00 | 09:21p 06:10a | Rise 05:15a 33%|
|Tue 6| 07:13a 08:17p 13:03 | 09:22p 06:08a | Rise 05:48a 24%|
|Wed 7| 07:12a 08:18p 13:06 | 09:24p 06:06a | Rise 06:14a 16%|
|Thu 8| 07:10a 08:19p 13:09 | 09:25p 06:04a | Rise 06:37a 9%|
|Fri 9| 07:08a 08:20p 13:12 | 09:27p 06:02a | Rise 06:57a 4%|
|Sat 10| 07:06a 08:22p 13:15 | 09:28p 06:00a | Rise 07:17a 1%|
+------+-----------------------+----------------+-----------------------+
|Sun 11| 07:05a 08:23p 13:18 | 09:30p 05:58a |New Set 08:03p 0%|
|Mon 12| 07:03a 08:24p 13:21 | 09:31p 05:56a | Set 09:05p 1%|
|Tue 13| 07:01a 08:25p 13:24 | 09:32p 05:54a | Set 10:08p 3%|
|Wed 14| 06:59a 08:27p 13:27 | 09:34p 05:52a | Set 11:11p 7%|
|Thu 15| 06:58a 08:28p 13:30 | 09:35p 05:50a | Set 12:14a 13%|
|Fri 16| 06:56a 08:29p 13:33 | 09:37p 05:48a | Set 01:15a 20%|
|Sat 17| 06:54a 08:30p 13:36 | 09:38p 05:46a | Set 02:12a 28%|
+------+-----------------------+----------------+-----------------------+
|Sun 18| 06:52a 08:32p 13:39 | 09:40p 05:44a | Set 03:03a 37%|
|Mon 19| 06:51a 08:33p 13:42 | 09:41p 05:42a | Set 03:47a 47%|
|Tue 20| 06:49a 08:34p 13:44 | 09:43p 05:40a |F Qtr Set 04:24a 57%|
|Wed 21| 06:47a 08:35p 13:47 | 09:45p 05:38a | Set 04:56a 67%|
|Thu 22| 06:46a 08:37p 13:50 | 09:46p 05:37a | Set 05:24a 77%|
|Fri 23| 06:44a 08:38p 13:53 | 09:48p 05:35a | Set 05:49a 86%|
|Sat 24| 06:43a 08:39p 13:56 | 09:49p 05:33a | Set 06:14a 93%|
+------+-----------------------+----------------+-----------------------+
|Sun 25| 06:41a 08:40p 13:59 | 09:51p 05:31a | Set 06:39a 98%|
|Mon 26| 06:39a 08:41p 14:02 | 09:52p 05:29a |Full Rise 08:19p 100%|
|Tue 27| 06:38a 08:43p 14:04 | 09:54p 05:27a | Rise 09:43p 99%|
|Wed 28| 06:36a 08:44p 14:07 | 09:55p 05:25a | Rise 11:06p 95%|
|Thu 29| 06:35a 08:45p 14:10 | 09:57p 05:23a | Rise 12:25a 88%|
|Fri 30| 06:33a 08:46p 14:13 | 09:59p 05:22a | Rise 01:34a 80%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunrise and sunset
Generated using my LookingUp for DOS program.
