Archive
Ephemeris: 12/09/2025 – Aldebaran, the “Follower”
This is Ephemeris for Tuesday, December 9th. Today the Sun will be up for 8 hours and 53 minutes, setting at 5:02, and it will rise tomorrow at 8:09. The Moon, 2 days before last quarter, will rise at 10:34 this evening.
Tonight will be the night of the earliest sunset of the year. For the last few nights the Sun has been setting within the same minute. Soon the Sun will set noticeably later.
The bright star Aldebaran appears at the lower left tip of a letter V group of stars laying on it’s side, the Hyades star cluster and the face of Taurus the Bull. It’s in the east in the evening, above Orion. Aldebaran isn’t actually part of the group. The cluster is about 153 light years away, while Aldebaran is 65. The star has an orange hue because its surface is cooler than the Sun’s. However, Aldebaran is 44 times larger in diameter, and shines 425 times brighter than the Sun. The name Aldebaran means “Follower” because it follows the Pleiades star cluster across the sky.
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
Ephemeris: 12/08/2025 – Hyades, half sisters of the Pleiades
This is Ephemeris for Monday, December 8th. Today the Sun will be up for 8 hours and 54 minutes, setting at 5:02, and it will rise tomorrow at 8:08. The Moon, 3 days before last quarter, will rise at 9:19 this evening.
At 8 o’clock this evening the constellation of Orion the hunter is still in the act of rising with one leg still stuck in the snow. What is above him is the constellation of Taurus the bull. His face is a letter V of stars or as a letter A, is the star cluster called the Hyades. In Greek myth the stars are the half sisters of the Pleiades, which are right above them. The Hyades star cluster is very special. They don’t look as splashy as the Pleiades which are younger and still have their hot blue white stars. However, the Hyades are much closer, a third as far as the Pleiades. In fact they’re close enough to be measured by trigonometry using Earth’s orbit as the base of a triangle, before satellites. Which was critical in measuring distances beyond the solar system.
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
Ephemeris: 12/05/2025 – I will be giving a talk about Ptolemy and his Almagest tonight
Event is Canceled – no heat in the building – postponed to next month
This is Ephemeris for Friday, December 5th. Today the Sun will be up for 8 hours and 57 minutes, setting at 5:02, and it will rise tomorrow at 8:05. The Moon, 1 day past full, will rise at 5:25 this evening.
Tonight at this month’s meeting of the Grand Traverse Astronomical Society which will be at 8 pm at Northwestern Michigan College’s Rogers Observatory. I will be giving an illustrated talk Ptolemy: The Good, Bad and the Ugly. His second century view of the universe held sway in the western world fourteen hundred years into the Christian era. He was a geographer, astronomer, and an astrologer. His greatest work, which I will explore, is known as the Almagest, meaning The Greatest in Arabic (Not his title). Afterward if it’s clear we’ll have a star party starting about 9 pm. The meeting will also be available via Zoom, which I’ll be using to give the talk. Go to gtastro.org for instructions and a link.
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
Ephemeris: 12/04/2025 – Orion survives a full moon
This is Ephemeris for Thursday, December 4th. Today the Sun will be up for 8 hours and 59 minutes, setting at 5:02, and it will rise tomorrow at 8:04. The Moon, at full today, will rise at 4:24 this evening.
While the full moon overpowers most stars, the bright stars of winter persist. This is even true with tonight’s supermoon, a bit larger and brighter than average. Nowhere in the sky is there a concentration of bright stars as there is in the winter sky. I know it’s not winter yet, but if you stay up late enough, say 10 PM, all the winter stars will be in the sky. Last to rise is the brightest star of all, Sirius. And by 10 o’clock will be low in the southeast. Jupiter has joined the winter stars this year, outshining them all. As a constellation the mighty hunter Orion is easiest to spot on a full moon night, containing seven very bright stars, with three bright stars in a straight line as his belt, which most folks find as his most distinctive feature.
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
Ephemeris: 12/03/2025 – Taking our weekly look at the whereabouts of the naked-eye planets
This is Bob Moler with Ephemeris for Wednesday, December 3rd. Today the Sun will be up for 9 hours, setting at 5:02, and it will rise tomorrow at 8:03. The Moon, 1 day before full, will set at 7:59 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. Saturn is the brightest star-like object in the southern sky as soon as it gets dark. In a telescope Saturn sports a very thin ring, 4/10ths of a degree from being edge on. The rings are slowly opening up. Normally, I’d say that Saturn’s rings are easy to see in a telescope. In a couple of months the rings will be much more visible in telescopes. Jupiter will rise at 8 PM in the east-northeast, beneath Castor and Pollux, the bright stars of Gemini. Jupiter’s 4 brightest moons can even be seen in binoculars, and shift position night to night. Mercury might be spotted low in the east-southeast by 7 AM tomorrow morning, having risen 45 minutes earlier.
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
Ephemeris: 12/02/2025 – Not the famous Comet ATLAS is breaking up
This is Bob Moler with Ephemeris for Tuesday, December 2nd. Today the Sun will be up for 9 hours and 1 minute, setting at 5:03, and it will rise tomorrow at 8:02. The Moon, 2 days before full, will set at 6:32 tomorrow morning.
I have a story about another comet ATLAS. This one is not the famous 3I/ATLAS, the interstellar interloper that is cruising through the inner solar system right now. It is another Comet ATLAS C/2025 K1, discovered in May, a little over a month before the famous one was. What we’re finding is that with comets, breaking up is not hard to do. It’s nucleus, the solid part of a comet, has broken into at least three separate pieces which are slowly separating. A comet’s nucleus is only a few miles in diameter. It is not tightly packed like a planet would be. One might think of them as kind of fluffy, especially this one, which is probably having it’s first go round close to the Sun. It appears to be an Oort cloud comet, who’s orbital period is thousands of years long.
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
Comets are named for the person or organization that discovered it. ATLAS is the Asteroid Terrestrial-Impact Last Alert System (ATLAS) search program. There’s a lot of comet ATLASes running around out there.
Ephemeris: 12/01/2025 – Previewing December skies
This is Ephemeris for Monday, December 1st. Today the Sun will be up for 9 hours and 3 minutes, setting at 5:03, and it will rise tomorrow at 8:01. The Moon, halfway from first quarter to full, will set at 5:06 tomorrow morning.
Let’s look ahead at the skies of December. We are now in the holiday season and about to celebrate the southernmost travel of the Sun in the sky and its return northward. The Sun will stop its travel south, the winter solstice on the 21st at 10:03 a.m. That will make that day the shortest day in terms of daylight hours. However, the earliest sunset and latest sunrise don’t coincide with that date. The earliest sunset it will be on the 9th just one minute earlier than today. The latest sunrise will be just a couple of days into next year. The reason is the Earth is closer to the Sun than average and is moving faster in its orbit than it normally does. It skews the sunrise and sunset times.
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
December Evening Star Chart
The planets and stars are plotted for the 15th at 9 pm 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, West 75° longitude. (An hour 45 minutes behind our daylight saving time meridian during EDT).
December 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 is in red.
- GemR on the star charts is the radiant of the Geminid meteor shower, which peaks on the morning of the 14th.
Twilight Limits, Nautical and Astronomical
| EST | |||||||
| Morning | Twilight | Evening | Twilight | Dark | Night | Moon | |
| Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
| 2025-12-01 | 6h17m | 6h52m | 18h12m | 18h47m | 3h45m | 6h17m | 0.89 |
| 2025-12-02 | 6h18m | 6h53m | 18h12m | 18h47m | 5h07m | 6h18m | 0.95 |
| 2025-12-03 | 6h19m | 6h54m | 18h12m | 18h47m | – | – | 0.99 |
| 2025-12-04 | 6h20m | 6h55m | 18h11m | 18h47m | – | – | 1.00 |
| 2025-12-05 | 6h20m | 6h56m | 18h11m | 18h47m | – | – | 0.98 |
| 2025-12-06 | 6h21m | 6h57m | 18h11m | 18h47m | – | – | 0.93 |
| 2025-12-07 | 6h22m | 6h57m | 18h11m | 18h47m | 18h47m | 19h59m | 0.86 |
| 2025-12-08 | 6h23m | 6h58m | 18h11m | 18h47m | 18h47m | 21h19m | 0.77 |
| 2025-12-09 | 6h24m | 6h59m | 18h11m | 18h47m | 18h47m | 22h35m | 0.67 |
| 2025-12-10 | 6h25m | 7h00m | 18h11m | 18h47m | 18h47m | 23h46m | 0.57 |
| 2025-12-11 | 6h25m | 7h01m | 18h11m | 18h47m | 18h47m | – | 0.47 |
| 2025-12-12 | 6h26m | 7h02m | 18h12m | 18h47m | 18h47m | 0h53m | 0.37 |
| 2025-12-13 | 6h27m | 7h02m | 18h12m | 18h47m | 18h47m | 1h59m | 0.28 |
| 2025-12-14 | 6h28m | 7h03m | 18h12m | 18h48m | 18h48m | 3h03m | 0.20 |
| 2025-12-15 | 6h28m | 7h04m | 18h12m | 18h48m | 18h48m | 4h08m | 0.13 |
| 2025-12-16 | 6h29m | 7h04m | 18h13m | 18h48m | 18h48m | 5h14m | 0.07 |
| 2025-12-17 | 6h30m | 7h05m | 18h13m | 18h48m | 18h48m | 6h20m | 0.03 |
| 2025-12-18 | 6h30m | 7h06m | 18h13m | 18h49m | 18h49m | 6h30m | 0.01 |
| 2025-12-19 | 6h31m | 7h06m | 18h14m | 18h49m | 18h49m | 6h31m | 0.00 |
| 2025-12-20 | 6h31m | 7h07m | 18h14m | 18h50m | 18h50m | 6h31m | 0.01 |
| 2025-12-21 | 6h32m | 7h07m | 18h15m | 18h50m | 18h50m | 6h32m | 0.04 |
| 2025-12-22 | 6h32m | 7h08m | 18h15m | 18h51m | 19h31m | 6h32m | 0.09 |
| 2025-12-23 | 6h33m | 7h08m | 18h16m | 18h51m | 20h41m | 6h33m | 0.16 |
| 2025-12-24 | 6h33m | 7h09m | 18h16m | 18h52m | 21h51m | 6h33m | 0.24 |
| 2025-12-25 | 6h33m | 7h09m | 18h17m | 18h52m | 23h02m | 6h33m | 0.33 |
| 2025-12-26 | 6h34m | 7h09m | 18h18m | 18h53m | – | 6h34m | 0.44 |
| 2025-12-27 | 6h34m | 7h10m | 18h18m | 18h54m | 0h13m | 6h34m | 0.55 |
| 2025-12-28 | 6h34m | 7h10m | 18h19m | 18h54m | 1h27m | 6h34m | 0.66 |
| 2025-12-29 | 6h35m | 7h10m | 18h20m | 18h55m | 2h44m | 6h35m | 0.76 |
| 2025-12-30 | 6h35m | 7h10m | 18h20m | 18h56m | 4h05m | 6h35m | 0.86 |
| 2025-12-31 | 6h35m | 7h10m | 18h21m | 19h01m | 5h28m | 6h35m | 0.93 |
| 2026-01-01 | 6h35m | 7h11m | 18h22m | 19h01m | – | – | 0.98 |
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
Dec 1 Mo Venus: 8.7° W
3 We 9:54 PM Moon-Pleiades: 0.8° S
4 Th 6:06 AM Moon Perigee: 357000 km
4 Th 6:14 PM Full Moon
5 Fr 4:51 PM Moon North Dec.: 28.3° N
7 Su 10:48 AM Moon-Jupiter: 3.7° S
7 Su 11:21 AM Moon-Pollux: 2.9° N
7 Su 3:59 PM Mercury Elongation: 20.7° W
8 Mo 9:23 AM Moon-Beehive: 1.5° S
10 We 1:32 AM Moon-Regulus: 0.8° S
11 Th 2:34 AM Moon Descending Node
11 Th 3:52 PM Last Quarter
14 Su 2:21 AM Geminid Shower: ZHR = 120
14 Su 11:27 AM Moon-Spica: 1.5° N
17 We 1:09 AM Moon Apogee: 406300 km
17 We 3:41 PM Jupiter-Pollux: 6.5° S
19 Fr 9:07 AM Mercury-Antares: 5.5° N
19 Fr 6:18 PM Moon South Dec.: 28.2° S
19 Fr 8:43 PM New Moon
21 Su 10:03 AM Winter Solstice
22 Mo 11:00 AM Ursid Shower: ZHR = 10
25 Th 5:03 PM Moon Ascending Node
26 Fr 10:24 PM Moon-Saturn: 4.2° S
27 Sa 2:10 PM First Quarter
31 We 8:21 AM Moon-Pleiades: 0.9° S
All event times are given for UTC-5, Eastern Standard 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.
Note that the site is now kept up for archival purposes. Fred Espenak retired from NASA several years ago and has recently passed away. His own site, AstroPixels, which is still up, contains much the same information: http://astropixels.com/almanac/almanac.html. However, it uses standard time all year.
Sun and Moon Rising and Setting Times
LU Ephemeris of Sky Events for Interlochen/TC
December, 2025 Local time zone: EST
+-----------------------------------------------------------------------+
| DATE | SUN SUN DAYLIGHT| TWILIGHT* |MOON RISE OR ILLUM |
| | RISE SET HOURS | END START |PHASE SET** TIME FRACTN|
+=======================================================================+
|Mon 1| 08:00a 05:03p 09:03 | 06:12p 06:50a | Set 05:06a 87%|
|Tue 2| 08:01a 05:03p 09:01 | 06:12p 06:51a | Set 06:32a 94%|
|Wed 3| 08:02a 05:02p 09:00 | 06:12p 06:52a | Set 07:59a 98%|
|Thu 4| 08:03a 05:02p 08:59 | 06:12p 06:53a |Full Rise 04:24p 100%|
|Fri 5| 08:04a 05:02p 08:57 | 06:12p 06:54a | Rise 05:25p 98%|
|Sat 6| 08:05a 05:02p 08:56 | 06:12p 06:55a | Rise 06:39p 94%|
+------+-----------------------+----------------+-----------------------+
|Sun 7| 08:06a 05:02p 08:55 | 06:12p 06:56a | Rise 07:59p 87%|
|Mon 8| 08:07a 05:02p 08:54 | 06:12p 06:57a | Rise 09:19p 78%|
|Tue 9| 08:08a 05:02p 08:53 | 06:12p 06:58a | Rise 10:34p 69%|
|Wed 10| 08:09a 05:02p 08:52 | 06:12p 06:59a | Rise 11:45p 59%|
|Thu 11| 08:10a 05:02p 08:51 | 06:12p 06:59a |L Qtr Rise 12:53a 49%|
|Fri 12| 08:11a 05:02p 08:51 | 06:12p 07:00a | Rise 01:58a 39%|
|Sat 13| 08:11a 05:02p 08:50 | 06:12p 07:01a | Rise 03:03a 30%|
+------+-----------------------+----------------+-----------------------+
|Sun 14| 08:12a 05:02p 08:49 | 06:13p 07:02a | Rise 04:08a 22%|
|Mon 15| 08:13a 05:02p 08:49 | 06:13p 07:02a | Rise 05:13a 14%|
|Tue 16| 08:14a 05:03p 08:49 | 06:13p 07:03a | Rise 06:19a 8%|
|Wed 17| 08:14a 05:03p 08:48 | 06:14p 07:04a | Rise 07:23a 4%|
|Thu 18| 08:15a 05:03p 08:48 | 06:14p 07:04a | Rise 08:22a 1%|
|Fri 19| 08:16a 05:04p 08:48 | 06:14p 07:05a |New Set 04:21p 0%|
|Sat 20| 08:16a 05:04p 08:48 | 06:15p 07:05a | Set 05:18p 1%|
+------+-----------------------+----------------+-----------------------+
|Sun 21| 08:17a 05:05p 08:48 | 06:15p 07:06a | Set 06:22p 4%|
|Mon 22| 08:17a 05:05p 08:48 | 06:16p 07:06a | Set 07:30p 8%|
|Tue 23| 08:18a 05:06p 08:48 | 06:17p 07:07a | Set 08:40p 14%|
|Wed 24| 08:18a 05:06p 08:48 | 06:17p 07:07a | Set 09:51p 22%|
|Thu 25| 08:18a 05:07p 08:48 | 06:18p 07:08a | Set 11:01p 31%|
|Fri 26| 08:19a 05:08p 08:49 | 06:18p 07:08a | Set 12:13a 41%|
|Sat 27| 08:19a 05:08p 08:49 | 06:19p 07:08a |F Qtr Set 01:26a 52%|
+------+-----------------------+----------------+-----------------------+
|Sun 28| 08:19a 05:09p 08:50 | 06:20p 07:09a | Set 02:43a 63%|
|Mon 29| 08:19a 05:10p 08:50 | 06:21p 07:09a | Set 04:04a 74%|
|Tue 30| 08:19a 05:11p 08:51 | 06:21p 07:09a | Set 05:28a 84%|
|Wed 31| 08:20a 05:12p 08:52 | 06:22p 07:09a | Set 06:49a 91%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunset and sunrise
Generated using my LookingUp for DOS program.
Ephemeris: 11/28/2025 – What will AI’s effect be on the future of society?
This is Ephemeris for Native American Heritage Day, Friday, November 28th. Today the Sun will be up for 9 hours and 8 minutes, setting at 5:04, and it will rise tomorrow at 7:57. The Moon, at first quarter today, will set at 1:12 tomorrow morning.
Let’s take one more look at AI this week. There is a real fear that artificial intelligence, AI, is displacing certain clerical jobs, and computer coding jobs. The latter is something I used to do. But I’m safe now, having retired 12 years ago. I have coded just about all the code I’ve ever needed to code. As AI takes more and more jobs, who’s gonna be able to afford to buy all the stuff the AI bots make? I’ve heard of some thoughts of a universal guaranteed income. How is that going to be funded? The rich, lower my taxes crowd, won’t go for that. Most people’s identity is defined by their job, what they do in their career. What could possibly replace that for most people?
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.
Ephemeris: 11/27/2025 – AIs, apparent knowledge without wisdom
This is Ephemeris for Thanksgiving Day, Thursday, November 27th. Today the Sun will be up for 9 hours and 9 minutes, setting at 5:05, and it will rise tomorrow at 7:56. The Moon, 1 day before first quarter, will set at midnight.
As the constellation Orion rises in the evening, the Native Americans around here would say the Winter Maker is rising, we are waiting for the glory of the winter constellations to appear and the bright Moon to disappear from the evening skies. I thought I’d talk about another topic this week. I am interested in, but really don’t know the depth of detail about: AI, artificial intelligence or what I’d rather call machine intelligence. It seems to me that there are a lot of folks being hooked on talking to these AI models such as ChatGPT and others as somebody or something that’s sympathetic to them. AIs are what you might call book smart or really Internet smart, but they’re not street smart. They were literally born yesterday, with all the wisdom that entails.
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.
Ephemeris: 11/26/2025 – Checking out the naked eye planets
This is Ephemeris for Wednesday, November 26th. Today the Sun will be up for 9 hours and 11 minutes, setting at 5:05, and it will rise tomorrow at 7:55. The Moon, 2 days before first quarter, will set at 10:49 this evening.
Pausing my exploration of AI to check out the naked eye planets this week. Mars and Mercury are too close to the Sun to be seen. Saturn is the brightest star like object in the southeastern sky as soon as it gets dark. In a telescope Saturn sports a very thin ring, 4/10ths of a degree from being edge on. In 4 days the rings will slowly start to open up. Normally, I’d say that Saturn’s rings are easy to see in a telescope. Currently, the rings appear extremely thin and can be difficult to pick up. Jupiter will rise at 8:29 PM in the east-northeast. Beneath Castor and Pollux, the bright stars of Gemini. By 7 AM, it will appear high in the west southwest, above the stars Procyon below and Sirius, near the horizon. Venus will rise at 7:04 in the east southeast and will probably not be visible.
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
Bob Moler's Ephemeris Blog 
