Archive
09/10/2021 – Ephemeris – Rescheduled virtual Sleeping Bear Dunes/GTAS star party set for tomorrow, Saturday night the 11th
This is Bob Moler with Ephemeris for Friday, September 10th. Today the Sun will be up for 12 hours and 46 minutes, setting at 8:02, and it will rise tomorrow at 7:17. The Moon, 3 days before first quarter, will set at 10:05 this evening.
Tomorrow night the Sleeping Bear Dunes National Lakeshore and the Grand Traverse Astronomical Society (GTAS) will host an online star party starting around 9 pm via the Zoom app available for Android smartphones, iPhones and computers. This is rescheduled from last week due to clouds. Instructions for joining are on the society’s website, gtastro.org. Images will be captured live from Northwestern Michigan College’s Joseph H Rogers Observatory. The images will be pretty much what is seen at the telescope eyepiece, and definitely not Hubble Space Telescope quality, which take weeks or months to process. Visible will be the five-day-old Moon, Venus, Jupiter, Saturn and the wonders of the Milky Way.
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
During the GTAS board meeting, September 3rd, just before the canceled star party, it was decided to hold off the decision on in person star parties until spring of 2022. We’ll follow the state of the pandemic in our area over the winter and see where we stand. Star parties at the Northwestern Michigan College’s Joseph H. Rogers Observatory could start in March. Star parties at the Sleeping Bear Dunes National Lakeshore have in the past started in April.
We may still use imagers on our telescopes to capture celestial objects for display on laptop computers rather than viewing through the eyepiece. The society has two imagers, and the Observatory another. The society’s imagers can be used on society’s and members telescopes. This will solve the problems of having to sanitize telescope eyepieces between observers. At this point, I’m not sure what sanitizing products do to the delicate anti-reflective coatings on eyepieces.
We will also pay more attention to viewing the heavens with the naked eye or binoculars that people may have. Bring your own. Learning the constellations is always the best way to be introduced to astronomy, and the only way, up until 411 years ago. And binoculars are a great first telescope.
02/01/2021 – Ephemeris – Previewing February Skies
This is Ephemeris for Monday, February 1st. Today the Sun will be up for 9 hours and 50 minutes, setting at 5:51, and it will rise tomorrow at 8:00. The Moon, 3 days before last quarter, will rise at 10:33 this evening. | February is the shortest month, even so the daylight hours throughout the month will be getting longer. Daylight hours will increase from 9 hours and 50 minutes today to 11 hours and 7 minutes on the 28th. The sunrise time will decrease from 8:01 today to 7:21 at months end. The sunset times will increase from 5:51 today to 6:29 on the 28th. Along with that the altitude of the Sun at noon will increase from 28.4 degrees today to 37.6 degrees at month’s end. It will be a degree lower for folks in the Straits area because they are a degree of latitude farther north. Local noon, by the way for Interlochen and Traverse City is about 12:56 p.m.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum

Star Chart for February 2021 (9 p.m. EST February 15, 2021). Created using my LookingUp program. Click on image to enlarge.
The planets and stars are plotted for the 15th at 9 p.m. 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. (An hour 45 minutes behind our daylight saving time meridian during EDT). To duplicate the star positions on a planisphere (rotating star finder) you may have to set it to 1 hour 45 minutes earlier than the current time.
Note the chart times of 9 p.m. and 6 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. 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.
February Morning Star Chart

Star Chart for February mornings 2021 (6 a.m. EST February 15, 2021). Created using my LookingUp program. Click on image to enlarge.
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.
- 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.
Twilight Limits, Nautical and Astronomical
EST | |||||||
Morning twilight | Evening twilight | Dark night | Moon | ||||
Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
2021-02-01 | 6h22m | 6h56m | 18h56m | 19h30m | 19h30m | 22h33m | 0.78 |
2021-02-02 | 6h21m | 6h55m | 18h57m | 19h31m | 19h31m | 23h48m | 0.67 |
2021-02-03 | 6h20m | 6h54m | 18h59m | 19h33m | 19h33m | – | 0.56 |
2021-02-04 | 6h19m | 6h53m | 19h00m | 19h34m | 19h34m | 1h03m | 0.45 |
2021-02-05 | 6h18m | 6h52m | 19h01m | 19h35m | 19h35m | 2h20m | 0.34 |
2021-02-06 | 6h16m | 6h50m | 19h02m | 19h36m | 19h36m | 3h35m | 0.23 |
2021-02-07 | 6h15m | 6h49m | 19h04m | 19h38m | 19h38m | 4h48m | 0.15 |
2021-02-08 | 6h14m | 6h48m | 19h05m | 19h39m | 19h39m | 5h54m | 0.08 |
2021-02-09 | 6h13m | 6h47m | 19h06m | 19h40m | 19h40m | 6h13m | 0.03 |
2021-02-10 | 6h12m | 6h46m | 19h08m | 19h41m | 19h41m | 6h12m | 0 |
2021-02-11 | 6h10m | 6h44m | 19h09m | 19h43m | 19h43m | 6h10m | 0 |
2021-02-12 | 6h09m | 6h43m | 19h10m | 19h44m | 19h44m | 6h09m | 0.02 |
2021-02-13 | 6h08m | 6h42m | 19h11m | 19h45m | 20h14m | 6h08m | 0.06 |
2021-02-14 | 6h06m | 6h40m | 19h13m | 19h47m | 21h19m | 6h06m | 0.12 |
2021-02-15 | 6h05m | 6h39m | 19h14m | 19h48m | 22h22m | 6h05m | 0.19 |
2021-02-16 | 6h04m | 6h37m | 19h15m | 19h49m | 23h25m | 6h04m | 0.27 |
2021-02-17 | 6h02m | 6h36m | 19h17m | 19h50m | – | 6h02m | 0.35 |
2021-02-18 | 6h01m | 6h34m | 19h18m | 19h52m | 0h27m | 6h01m | 0.45 |
2021-02-19 | 5h59m | 6h33m | 19h19m | 19h53m | 1h30m | 5h59m | 0.54 |
2021-02-20 | 5h58m | 6h32m | 19h21m | 19h54m | 2h33m | 5h58m | 0.64 |
2021-02-21 | 5h56m | 6h30m | 19h22m | 19h56m | 3h35m | 5h56m | 0.73 |
2021-02-22 | 5h55m | 6h28m | 19h23m | 19h57m | 4h34m | 5h55m | 0.81 |
2021-02-23 | 5h53m | 6h27m | 19h24m | 19h58m | 5h28m | 5h53m | 0.89 |
2021-02-24 | 5h52m | 6h25m | 19h26m | 19h59m | – | – | 0.94 |
2021-02-25 | 5h50m | 6h24m | 19h27m | 20h01m | – | – | 0.98 |
2021-02-26 | 5h48m | 6h22m | 19h28m | 20h02m | – | – | 1 |
2021-02-27 | 5h47m | 6h20m | 19h30m | 20h03m | – | – | 0.99 |
2021-02-28 | 5h45m | 6h19m | 19h31m | 20h05m | 20h05m | 20h16m | 0.95 |
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/2019/09/27/
NASA Calendar of Planetary Events
Date Time Event Feb 1 Mo Venus: 13° W 3 We 2:33 pm Moon Perigee: 370,100 km 4 Th 12:37 pm Last Quarter 6 Sa 7:29 pm Moon Descending Node 8 Mo 8:39 am Mercury Inferior Conjunction 8 Mo 10:34 am Moon South Dec.: 25° S 11 Th 2:06 pm New Moon 18 Th 5:22 am Moon Apogee: 404,500 km 18 Th 5:47 pm Moon-Mars: 4.1° N 19 Fr 1:47 pm First Quarter 20 Sa 8:44 pm Moon Ascending Node 22 Mo 7:12 pm Moon North Dec.: 25.1° N 23 Tu 2:38 am Mercury-Saturn: 4° N 24 We 7:16 pm Moon-Beehive: 2.5° S 27 Sa 3:17 am Full Moon
All event times are given for UTC-5:00: Eastern Standard or Daylight 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.
Sun and Moon Rising and Setting Events
LU Ephemeris of Sky Events for Interlochen/TC February, 2021 Local time zone: EST +-----------------------------------------------------------------------+ | DATE | SUN SUN DAYLIGHT| TWILIGHT* |MOON RISE OR ILLUM | | | RISE SET HOURS | END START |PHASE SET** TIME FRACTN| +=======================================================================+ |Mon 1| 08:01a 05:51p 09:50 | 06:57p 06:55a | Rise 10:33p 79%| |Tue 2| 08:00a 05:53p 09:53 | 06:59p 06:54a | Rise 11:48p 69%| |Wed 3| 07:59a 05:54p 09:55 | 07:00p 06:53a | Rise 01:03a 58%| |Thu 4| 07:57a 05:56p 09:58 | 07:01p 06:52a |L Qtr Rise 02:19a 47%| |Fri 5| 07:56a 05:57p 10:00 | 07:03p 06:51a | Rise 03:35a 36%| |Sat 6| 07:55a 05:59p 10:03 | 07:04p 06:50a | Rise 04:48a 25%| +------+-----------------------+----------------+-----------------------+ |Sun 7| 07:54a 06:00p 10:06 | 07:05p 06:48a | Rise 05:53a 16%| |Mon 8| 07:52a 06:01p 10:09 | 07:06p 06:47a | Rise 06:49a 9%| |Tue 9| 07:51a 06:03p 10:11 | 07:08p 06:46a | Rise 07:35a 4%| |Wed 10| 07:49a 06:04p 10:14 | 07:09p 06:45a | Rise 08:11a 1%| |Thu 11| 07:48a 06:06p 10:17 | 07:10p 06:43a |New Set 05:57p 0%| |Fri 12| 07:47a 06:07p 10:20 | 07:12p 06:42a | Set 07:07p 2%| |Sat 13| 07:45a 06:08p 10:23 | 07:13p 06:41a | Set 08:14p 5%| +------+-----------------------+----------------+-----------------------+ |Sun 14| 07:44a 06:10p 10:26 | 07:14p 06:39a | Set 09:19p 11%| |Mon 15| 07:42a 06:11p 10:29 | 07:15p 06:38a | Set 10:22p 17%| |Tue 16| 07:41a 06:13p 10:32 | 07:17p 06:37a | Set 11:24p 25%| |Wed 17| 07:39a 06:14p 10:34 | 07:18p 06:35a | Set 12:27a 34%| |Thu 18| 07:38a 06:15p 10:37 | 07:19p 06:34a | Set 01:30a 43%| |Fri 19| 07:36a 06:17p 10:40 | 07:21p 06:32a |F Qtr Set 02:32a 52%| |Sat 20| 07:34a 06:18p 10:43 | 07:22p 06:31a | Set 03:34a 61%| +------+-----------------------+----------------+-----------------------+ |Sun 21| 07:33a 06:20p 10:46 | 07:23p 06:29a | Set 04:33a 71%| |Mon 22| 07:31a 06:21p 10:49 | 07:25p 06:28a | Set 05:28a 79%| |Tue 23| 07:30a 06:22p 10:52 | 07:26p 06:26a | Set 06:15a 87%| |Wed 24| 07:28a 06:24p 10:55 | 07:27p 06:25a | Set 06:56a 93%| |Thu 25| 07:26a 06:25p 10:58 | 07:28p 06:23a | Set 07:30a 98%| |Fri 26| 07:24a 06:26p 11:01 | 07:30p 06:21a | Set 07:59a 100%| |Sat 27| 07:23a 06:28p 11:05 | 07:31p 06:20a |Full Rise 06:59p 99%| +------+-----------------------+----------------+-----------------------+ |Sun 28| 07:21a 06:29p 11:08 | 07:32p 06:18a | Rise 08:16p 96%| +-----------------------------------------------------------------------+ * Nautical Twilight ** Moonrise or moonset, whichever occurs between sunrise and sunset
Created using my LookingUp for DOS output as HTML.