Ephemeris: 12/11/2023 – This is the week of the Geminid meteor shower
This is Bob Moler with Ephemeris for Monday, December 11th. Today the Sun will be up for 8 hours and 52 minutes, setting at 5:02, and it will rise tomorrow at 8:10. The Moon, 1 day before new, will rise at 8:09 tomorrow morning.
The Geminid meteor shower will reach its peak this week, well Thursday afternoon, actually. I’m talking about this early hoping that we might get a clear night this week to see them. The Geminids are the most active annual meteor shower. Up to 120 meteors may be visible per hour at its peak when it’s the radiant in Gemini is directly overhead which would be on Wednesday or Thursday mornings this week. At those times it will be about half a day before or after the peak, but with such a high number of meteors it should be a spectacular show anyway. The Geminids are produced by a rock comet called Phaethon, which was discovered in 1983 by the Infrared Astronomy Satellite, the first to perform an infrared survey of the entire sky.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
The Geminids are supposed to reach about 120 an hour at peak which would be at one or two in the morning which is about 12 hours after their actual peak. So that we won’t get the 120, but there’s an equal chance to spot them on the night of the 13/14th or 14/15th. Click or tap on the image to enlarge it. Image created using my Looking Up app.
Ephemeris: 12/08/2023 – Tomorrow has the earliest sunset of the year
This is Ephemeris for Friday, December 8th. Today the Sun will be up for 8 hours and 55 minutes, setting at 5:02, and it will rise tomorrow at 8:08. The Moon, 3 days past last quarter, will rise at 4:28 tomorrow morning.
Tomorrow is the date of the earliest sunset, in the middle of a 12-day stretch where the Sun sets within the same minute. We are still 13 days from the winter solstice, the day of the shortest daylight hours, on the 21st. The reason is twofold. The Sun is near its farthest position south of the equator, where the longitude lines are closer together, so it takes less time to cross them. 15 degrees in longitude equals one hour in Earth’s rotation. Add to that we are less than a month from Earth’s perihelion in its orbit of the Sun, that is at its closest, and is moving faster than average. The combined effects delay sunrise and sunset, from what they’d be if the Sun was on the equator and the Earth’s orbit was circular. We will have our latest sunrise on January 2nd.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
In December the Earth is approaching perihelion, its closest to the Sun, so it moves faster than average. This makes the Sun to appear to move faster eastward against the stars in our sky, and tends to make our sunrises, apparent local noons and sunsets later than they would otherwise be. Sunset bottoms out early and extends the date of the latest sunrise
For the June or summer solstice around here, the Earth is near aphelion, it’s farthest from the Sun where the Earth is at its slowest in its orbit. By reflection, the Sun appears to move its slowest against the stars in our sky. This effect works against the high latitude effect, making the effect smaller. Looking at the table above, the days between the earliest and latest times is shorter for the summer solstice than for the winter solstice.
Ephemeris: 12/07/2023 – Auriga, the charioteer
This is Ephemeris for Thursday, December 7th. Today the Sun will be up for 8 hours and 56 minutes, setting at 5:02, and it will rise tomorrow at 8:07. The Moon, 2 days past last quarter, will rise at 3:20 tomorrow morning.
The first constellation of winter is in the northeastern sky, called Auriga the charioteer. It’s to the upper left of Orion and directly left of Taurus. Auriga actually never really quite leaves us, because its brightest star, Capella is the star that never leaves us even in the heat of summer, Though for most of us it’s in the trees in the north. Auriga is a pentagon of stars with the Capella on top. Just right of Capella is a thin triangle of three faint stars, an asterism or informal constellation called the Kids, baby goats. Capella is their mother. For some reason they are all held by a charioteer, who is without his chariot. And from all the Hollywood Biblical epic movies I’ve seen, it takes two hands to drive a chariot, and it doesn’t have a rumble seat.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
Ephemeris: 12/06/2023 – Our weekly look at the naked-eye planets
This is Ephemeris for Wednesday, December 6th. Today the Sun will be up for 8 hours and 57 minutes, setting at 5:02, and it will rise tomorrow at 8:06. The Moon, 1 day past last quarter, will rise at 2:15 tomorrow morning.
Let’s find out where the naked-eye planets have wandered off to this week. Three of those five planets are now visible, but Mercury sets too close to sunset to be seen. Mars rises too close to sunrise. Saturn and Jupiter are the only evening planets visible. Saturn can be seen moving from the south-southwest to setting in the west-southwest at 11:12 pm. Jupiter will be moving from the southeast to southwest and will be much higher in the sky during the evening hours than Saturn is, and will be up most of the night until 4:56 am. Venus, the brilliant morning star, will rise in the east-southeast at 4:22 am, and be a brilliant beacon in the morning. It will be far below and left of the fat crescent Moon.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Ephemeris: 12/05/2023 – The Hyades, face of Taurus and an important star cluster
This is Bob Moler with Ephemeris for Tuesday, December 5th. Today the Sun will be up for 8 hours and 58 minutes, setting at 5:02, and it will rise tomorrow at 8:05. The Moon, at last quarter today, will rise at 1:11 tomorrow morning.
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 up above him is the constellation of Taurus the bull. His face is a letter V of stars or as a letter A, as I mentioned yesterday, 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 in fact they’re close enough to be measured by trigonometry using the earth’s orbit as the base of a triangle, like surveyors would do on Earth.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
Ephemeris: 12/04/2023 – Our Alphabet begins with Taurus, and that’s no Bull!
This is Ephemeris for Monday, 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, 1 day before last quarter, will rise at 12:08 tomorrow morning.
In the eastern part of the sky at 8 pm tonight, above the rising constellation of Orion the hunter, with its three belt stars nearly vertical and its two brightest stars Betelgeuse and Rigel, is an orange star called Aldebaran at one end of a letter V shape of stars which is the face of the constellation Taurus the bull. The V shape of stars is called the Hyades which were the half sisters of the Pleiades above them, according to Greek myth. Back 4,000 or so years ago when alphabets were being invented the vernal equinox or the beginning of spring where the sun was entering was Taurus, rather than Aries, or Pisces as it does today. The Mesopotamians took the shape of the head of Taurus to be the first letter of their alphabet, Aleph, which was an A lying on its side. In early Egyptian hieroglyphics it was the head of a bull. Over time the A got turned around so it was standing on its two legs with its apex on top and a bar across it to become the A we know today.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
Ephemeris: 12/01/2023 – I’ll be exploring ancient Greek astronomy tonight
This is Ephemeris for Friday, December 1st. Today the Sun will be up for 9 hours and 4 minutes, setting at 5:03, and it will rise tomorrow at 8:00. The Moon, halfway from full to last quarter, will rise at 8:51 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 about The Astronomy of the Ancient Greeks. The Greek astronomical view of the universe held sway in the western world sixteen hundred years into the Christian era. I’ll look at the early Greek astronomers from Thales, the first astronomer and philosopher in the 6th century BCE to Ptolemy in the 2nd century CE. 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 are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
Ephemeris: 11/30/2023 – Previewing December skies
This is Ephemeris for Thursday, November 30th. Today the Sun will be up for 9 hours and 5 minutes, setting at 5:04, and it will rise tomorrow at 7:59. The Moon, 3 days past full, will rise at 7:44 this evening. | December is the month with the shortest daylight hours. Winter will officially arrive at the winter solstice on the 21st at 10:28 p.m. There will be little movement in the sunset times: In the Traverse City/Interlochen area this will be from 5:03 Tomorrow, down to 5:02 and then advancing to 5:11 at the end of the month. There is more movement in the sunrise times which will advance from 7:59 am tomorrow to 8:20 am on the 31st. There is also little movement of daylight hours. The noontime Sun will hang around 22 to 23 degrees above the southern horizon all month. The Geminid meteors on the night of the14th and morning of the 15th will have dark skies all night. It is the most active shower of the year, difficult to view from here due to the cold and December’s cloudiness.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
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 evening of the 14th.
Twilight Limits, Nautical and Astronomical
| EST | |||||||
| Morning | Twilight | Evening | Twilight | Dark | Night | Moon | |
| Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
| 2023-12-01 | 6h20m | 6h55m | 18h16m | 18h51m | 18h51m | 20h51m | 0.77 |
| 2023-12-02 | 6h21m | 6h56m | 18h16m | 18h51m | 18h51m | 21h58m | 0.69 |
| 2023-12-03 | 6h22m | 6h57m | 18h16m | 18h51m | 18h51m | 23h04m | 0.60 |
| 2023-12-04 | 6h23m | 6h58m | 18h15m | 18h51m | 18h51m | – | 0.51 |
| 2023-12-05 | 6h24m | 6h59m | 18h15m | 18h51m | 18h51m | 0h09m | 0.41 |
| 2023-12-06 | 6h25m | 7h00m | 18h15m | 18h50m | 18h50m | 1h12m | 0.32 |
| 2023-12-07 | 6h26m | 7h01m | 18h15m | 18h50m | 18h50m | 2h15m | 0.23 |
| 2023-12-08 | 6h27m | 7h02m | 18h15m | 18h50m | 18h50m | 3h21m | 0.15 |
| 2023-12-09 | 6h27m | 7h03m | 18h15m | 18h51m | 18h51m | 4h28m | 0.09 |
| 2023-12-10 | 6h28m | 7h04m | 18h15m | 18h51m | 18h51m | 5h40m | 0.04 |
| 2023-12-11 | 6h29m | 7h04m | 18h15m | 18h51m | 18h51m | 6h29m | 0.01 |
| 2023-12-12 | 6h30m | 7h05m | 18h16m | 18h51m | 18h51m | 6h30m | 0.00 |
| 2023-12-13 | 6h30m | 7h06m | 18h16m | 18h51m | 18h51m | 6h30m | 0.02 |
| 2023-12-14 | 6h31m | 7h07m | 18h16m | 18h51m | 18h51m | 6h31m | 0.06 |
| 2023-12-15 | 6h32m | 7h07m | 18h16m | 18h52m | 19h50m | 6h32m | 0.13 |
| 2023-12-16 | 6h33m | 7h08m | 18h16m | 18h52m | 21h12m | 6h33m | 0.22 |
| 2023-12-17 | 6h33m | 7h09m | 18h17m | 18h52m | 22h33m | 6h33m | 0.32 |
| 2023-12-18 | 6h30m | 7h05m | 18h13m | 18h49m | 23h51m | 6h30m | 0.43 |
| 2023-12-19 | 6h30m | 7h06m | 18h14m | 18h49m | – | 6h30m | 0.55 |
| 2023-12-20 | 6h31m | 7h06m | 18h14m | 18h50m | 1h07m | 6h31m | 0.66 |
| 2023-12-21 | 6h31m | 7h07m | 18h14m | 18h50m | 2h22m | 6h31m | 0.76 |
| 2023-12-22 | 6h32m | 7h07m | 18h15m | 18h50m | 3h37m | 6h32m | 0.85 |
| 2023-12-23 | 6h32m | 7h08m | 18h16m | 18h51m | 4h53m | 6h32m | 0.92 |
| 2023-12-24 | 6h33m | 7h08m | 18h16m | 18h52m | 6h09m | 6h33m | 0.97 |
| 2023-12-25 | 6h33m | 7h09m | 18h17m | 18h52m | – | – | 0.99 |
| 2023-12-26 | 6h34m | 7h09m | 18h17m | 18h53m | – | – | 1.00 |
| 2023-12-27 | 6h34m | 7h09m | 18h18m | 18h53m | – | – | 0.99 |
| 2023-12-28 | 6h34m | 7h10m | 18h19m | 18h54m | – | – | 0.95 |
| 2023-12-29 | 6h35m | 7h10m | 18h19m | 18h55m | 18h55m | 19h43m | 0.90 |
| 2023-12-30 | 6h35m | 7h10m | 18h20m | 18h56m | 18h56m | 20h50m | 0.84 |
| 2023-12-31 | 6h35m | 7h10m | 18h21m | 18h56m | 18h56m | 21h55m | 0.77 |
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 Fr Venus: 42.9° W
1 Fr 11:21 pm Moon-Beehive: 3.9° S
4 Mo 8:59 am Mercury Elongation: 21.3° E
4 Mo 1:42 pm Moon Apogee: 404,300 km
5 Tu 12:49 am Last Quarter
8 Fr 9:05 am Moon-Spica: 2.5° S
8 Fr 10:24 am Moon Descending Node
9 Sa 11:53 am Moon-Venus: 3.9° N
12 Tu 6:32 pm New Moon
13 We 4:51 pm Moon South Dec.: 28.2° S
14 Th 2:02 pm Geminid Shower: ZHR = 120!
16 Sa 1:53 pm Moon Perigee: 367,900 km
17 Su 4:58 pm Moon-Saturn: 2.5° N
19 Tu 1:39 pm First Quarter
21 Th 8:54 am Moon Ascending Node
21 Th 10:28 pm Winter Solstice
22 Fr 9:20 am Moon-Jupiter: 2.7° S
22 Fr 1:45 pm Mercury Inferior Conj.
22 Fr 10:00 pm Ursid Shower: ZHR = 10
24 Su 2:37 am Moon-Pleiades: 1.1° N
26 Tu 4:50 pm Moon North Dec.: 28.1° N
26 Tu 7:33 pm Full Cold Moon
28 Th 6:51 am Moon-Pollux: 1.9° N
29 Fr 7:45 am Moon-Beehive: 3.7° S
Jan 1 Mo Venus: 37.4° W
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.
Sun and Moon Rising and Setting Events
LU Ephemeris of Sky Events for Interlochen/TC
December, 2023 Local time zone: EST
+-----------------------------------------------------------------------+
| DATE | SUN SUN DAYLIGHT| TWILIGHT* |MOON RISE OR ILLUM |
| | RISE SET HOURS | END START |PHASE SET** TIME FRACTN|
+=======================================================================+
|Fri 1| 07:59a 05:03p 09:04 | 06:13p 06:50a | Rise 08:51p 79%|
|Sat 2| 08:00a 05:03p 09:02 | 06:12p 06:51a | Rise 09:58p 71%|
+------+-----------------------+----------------+-----------------------+
|Sun 3| 08:01a 05:03p 09:01 | 06:12p 06:52a | Rise 11:04p 62%|
|Mon 4| 08:02a 05:02p 08:59 | 06:12p 06:53a | Rise 12:08a 52%|
|Tue 5| 08:04a 05:02p 08:58 | 06:12p 06:54a |L Qtr Rise 01:11a 43%|
|Wed 6| 08:05a 05:02p 08:57 | 06:12p 06:55a | Rise 02:15a 34%|
|Thu 7| 08:06a 05:02p 08:56 | 06:12p 06:56a | Rise 03:20a 25%|
|Fri 8| 08:07a 05:02p 08:55 | 06:12p 06:56a | Rise 04:28a 17%|
|Sat 9| 08:08a 05:02p 08:54 | 06:12p 06:57a | Rise 05:40a 10%|
+------+-----------------------+----------------+-----------------------+
|Sun 10| 08:08a 05:02p 08:53 | 06:12p 06:58a | Rise 06:54a 5%|
|Mon 11| 08:09a 05:02p 08:52 | 06:12p 06:59a | Rise 08:09a 1%|
|Tue 12| 08:10a 05:02p 08:51 | 06:12p 07:00a |New Set 04:26p 0%|
|Wed 13| 08:11a 05:02p 08:50 | 06:12p 07:01a | Set 05:22p 2%|
|Thu 14| 08:12a 05:02p 08:50 | 06:13p 07:01a | Set 06:31p 5%|
|Fri 15| 08:13a 05:02p 08:49 | 06:13p 07:02a | Set 07:50p 12%|
|Sat 16| 08:13a 05:03p 08:49 | 06:13p 07:03a | Set 09:11p 20%|
+------+-----------------------+----------------+-----------------------+
|Sun 17| 08:14a 05:03p 08:48 | 06:13p 07:03a | Set 10:32p 30%|
|Mon 18| 08:15a 05:03p 08:48 | 06:14p 07:04a | Set 11:50p 41%|
|Tue 19| 08:15a 05:04p 08:48 | 06:14p 07:05a |F Qtr Set 01:06a 53%|
|Wed 20| 08:16a 05:04p 08:48 | 06:15p 07:05a | Set 02:21a 64%|
|Thu 21| 08:16a 05:04p 08:48 | 06:15p 07:06a | Set 03:37a 74%|
|Fri 22| 08:17a 05:05p 08:48 | 06:16p 07:06a | Set 04:53a 83%|
|Sat 23| 08:17a 05:05p 08:48 | 06:16p 07:07a | Set 06:08a 90%|
+------+-----------------------+----------------+-----------------------+
|Sun 24| 08:18a 05:06p 08:48 | 06:17p 07:07a | Set 07:21a 96%|
|Mon 25| 08:18a 05:07p 08:48 | 06:17p 07:07a | Set 08:25a 99%|
|Tue 26| 08:18a 05:07p 08:48 | 06:18p 07:08a |Full Rise 04:30p 100%|
|Wed 27| 08:19a 05:08p 08:49 | 06:19p 07:08a | Rise 05:30p 99%|
|Thu 28| 08:19a 05:09p 08:49 | 06:19p 07:08a | Rise 06:35p 96%|
|Fri 29| 08:19a 05:10p 08:50 | 06:20p 07:09a | Rise 07:43p 91%|
|Sat 30| 08:19a 05:10p 08:51 | 06:21p 07:09a | Rise 08:50p 85%|
+------+-----------------------+----------------+-----------------------+
|Sun 31| 08:20a 05:11p 08:51 | 06:22p 07:09a | Rise 09:55p 78%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunrise and sunset
Generated using my LookingUp for DOS program.
Ephemeris: 11/29/2023 – Where are the naked-eye planets this week?
This is Ephemeris for Wednesday, November 29th. Today the Sun will be up for 9 hours and 7 minutes, setting at 5:04, and it will rise tomorrow at 7:58. The Moon, 2 days past full, will rise at 6:42 this evening.
Let’s find out where the naked-eye planets have wandered off to this week. Three of those five planets are now visible, but Mercury sets too close to sunset to be seen, and Mars rises too close to sunrise. Saturn and Jupiter are the only evening planets visible. Saturn can be seen moving from the south-southwest to setting in the west-southwest in the evening. Ringed planet will be setting at 11:34 pm. Jupiter will be moving from the east-southeast to southwest and will be much higher in the sky during the evening hours than Saturn is, and will be up most of the night until 5:22 am. Venus, the brilliant morning star, will rise in the east-northeast at 4:09 am, and be a brilliant beacon in the morning.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
Ephemeris: 11/28/2023 – The new Moon Race
This is Bob Moler with Ephemeris for Tuesday, November 28th. Today the Sun will be up for 9 hours and 8 minutes, setting at 5:05, and it will rise tomorrow at 7:57. The Moon, 1 day past full, will rise at 5:47 this evening.
Now, in the third decade of the 21st century, 50 years since Neil Armstrong set foot on the moon, there’s now a big rush by many nations and some private companies to send missions to the moon, with orbiters and landers. The biggest and most expensive project is the United States Artemis project which has launched one of the SLS rockets to the moon and will send another one probably later next year in preparation for a landing, in a year or two after that. Earlier this year India successfully landed a probe on the Moon with a rover for less cost that it would take Hollywood to make a movie about it. They are making noises about sending a manned mission to the moon by 2040. Stay tuned, we have an exciting decade of lunar exploration coming up.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
Bob Moler's Ephemeris Blog 
