Ephemeris: 12/10/2024 – Jupiter’s four bright moons
This is Ephemeris for Tuesday, December 10th. 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, 2 days past first quarter, will set at 3:39 tomorrow morning.
The bright star like object in the east in the evenings is the planet Jupiter. If one were to look at Jupiter through binoculars it would appear somewhat larger than a star would look. It has several dimmer stars from one side to the other of it, and if one looked the next night those little stars would have moved. Those are not stars at all, but the four largest moons of Jupiter. This would be easily apparent in the telescope. These are the four Galilean moons. They were observed by Galileo in either late 1609 or early 1610. Another astronomer, Simon Marius discovered these moons at about the same time, but Galileo was first to publish. So he gets the honor. However, Simon Marius is the one who gave them the names we know them by today. Their names, in order of their distance from Jupiter, are: Io, Europa, Ganymede, and Callisto. Each is a fascinating world in its own right.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
The periods of these satellites is interesting. Io orbits Jupiter in 1.8 days. Europa orbits in 3.6 days twice as long as Io. Ganymede orbits Jupiter in 7.2 days which is twice as long as Europa. Callisto takes 16.7 days to orbit Jupiter, and that is longer than twice Ganymede’s orbital period, and so is not in resonance with Ganymede. So the first three are in a 2:1orbital resonance with each other.
Ephemeris: 12/09/2024 – Today’s sunset is the earliest of the year
This is Ephemeris for Monday, 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, 1 day past first quarter, will set at 2:20 tomorrow morning.
Today is the date of the earliest sunset, in the middle of a 13-day stretch where the Sun sets within the same minute. We are still 12 days from the winter solstice, the day of the shortest daylight hours, on the 21st. The reason is twofold. The Sun is approaching 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 stayed 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). Times will be different for other locations.
Addendum
Ephemeris: 12/06/2024 – Historical search for the Star of Bethlehem tonight
This is Ephemeris for Friday, December 6th. Today the Sun will be up for 8 hours and 56 minutes, setting at 5:02, and it will rise tomorrow at 8:06. The Moon, 2 days before first quarter, will set at 10:31 this evening.
Tonight at 8 p.m. I will be giving a talk investigating what the Star of Bethlehem may have been. This will be at Northwestern Michigan College’s Rogers Observatory located south of Traverse City on Birmley Road. The talk is a scientific treatment of the matter, rather than a religious one. We’ll look at the usual suspects for what the star may have been. And we’ll see what the Gospel writers may have gotten right and possibly wrong. We’ll look at historical writings and recorded Chinese observations of the heavens around that time. I will augment this with computer simulations of what might be important celestial events visible around that time. There is no admission charge. There will be viewing of the skies afterward if it’s clear.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 12/05/2024 – More about Jupiter: it’s very gassy
This is Bob Moler with Ephemeris for Thursday, 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, 3 days before first quarter, will set at 9:14 this evening.
The planet Jupiter rules over the night sky with the Moon after Venus sets. Jupiter, 11 times the diameter of the Earth, has the volume of 1300 earths, however it is only 318 times the mass of the Earth. It is made-up mostly of hydrogen and helium, so it is called a gas giant planet, rather than a terrestrial or rocky planet like the Earth. Jupiter is the best viewable of the planets in a small telescope. It has 2 dark bands across it called belts of darker appearing clouds. The famed Great Red Spot is an anticyclone embedded in the southern of those belts. The spot is not as red anymore. I remember it being brick-red back in the late 1950s and early 60s. Jupiter spins very rapidly, its day lasts only 10 hours.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 12/04/2024 – Checking where the naked-eye planets are now
This is Ephemeris for Wednesday, December 4th. Today the Sun will be up for 8 hours and 58 minutes, setting at 5:02, and it will rise tomorrow at 8:04. The Moon, 3 days past new, will set at 7:59 this evening.
Let’s take our weekly look at the whereabouts of the naked-eye planets. Venus can be spotted low in the south-southwestern sky by 5:30 PM, about 30 minutes after sunset. It appears above the Moon tonight, and will set at 8:09 PM. Saturn will be in the south-southeast at 6 PM. Jupiter will rise at 5:09 PM in the east-northeast, and be a good object for the small telescope about an hour later. Mars, rises tonight at 8:47, Both Mars and Jupiter are considered morning planets, since they are still up at sunrise, though Jupiter will be an evening planet after Saturday. By 6:00 AM tomorrow Jupiter will be in the west, above and right of Orion, while reddish Mars will be high in the southwest. Jupiter and Saturn are great planets to view with a small telescope.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 12/03/2024 – Jupiter begins to dominate the evening sky
This is Ephemeris for Tuesday, December 3rd. Today the Sun will be up for 9 hours even, setting at 5:02, and it will rise tomorrow at 8:03. The Moon, 2 days past new, will set at 6:48 this evening.
The bright star that’s in the east early in the evenings isn’t a star at all, but the planet Jupiter. This giant planet is moving to be in opposition to the Sun this Saturday, which means that the Earth is directly between Jupiter and the Sun, so it’s the time that it’s closest to us. And so it’s at its largest appearing and brightest. Jupiter is the largest of the planets being about 11 times the Earth’s diameter, its volume would be 11 cubed or about 1,300 times the Earth’s volume. It is the second-brightest planet after Venus. It is also the largest appearing planet in telescopes except for a couple of months around the time when Venus is closest to the Earth. Binoculars will show that Jupiter is not quite star-like, and some of its large satellites can be also seen.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 12/02/2024 – Orion is rising in the evening
This is Ephemeris for Monday, 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, 1 day past new, will set at 5:47 this evening.
In the east, the central winter constellation Orion the hunter throws a leg over the horizon between 8 and 9 p.m. as Robert Frost told in his poem Star-Splitter. The upright rectangle that is his body on December evenings is tilted to the left as he rises, with a bright red star Betelgeuse at the top left of the rectangle, his shoulder. At the opposite corner is blue-white Rigel, a knee. In the center of the rectangle is a line of three stars nearly vertically aligned as he rises, which represents his belt. The stars of Orion’s belt are how many folks can find him. The Anishinaabek native peoples of this area call him the Wintermaker whose arms are held wide to encompass the winter stars. His rising in the evening heralds the coming of winter.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 11/29/2024 – Previewing December skies
This is Ephemeris for Native American Heritage Day, Friday, November 29th. 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, 2 days before new, will rise at 7:39 tomorrow morning.
Let’s look at December skies. We are now in the holiday season and about to celebrate the southernmost travel of the Sun in the sky and its return northward. So there is not much change in sunrise and sunset times. The Sun will stop its travel south, the winter solstice, on the 21st at 4:20 am. It will make that day the shortest day in terms of daylight hours. However, the earliest sunset will occur on the 9th. The Geminid meteor shower will be hampered by the bright Moon when it reaches its peak on the evening of the 13th, near the full moon. This month continues the surprisingly active sunspot cycle that started four years ago and is nearing its peak.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum (Updated 11/29/2024)
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 13th.
Twilight Limits, Nautical and Astronomical
| EST | |||||||
| Morning | Twilight | Evening | Twilight | Dark | Night | Moon | |
| Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
| 2024-12-01 | 6h17m | 6h52m | 18h12m | 18h47m | 18h47m | 6h17m | 0.01 |
| 2024-12-02 | 6h18m | 6h53m | 18h12m | 18h47m | 18h47m | 6h18m | 0.04 |
| 2024-12-03 | 6h19m | 6h54m | 18h12m | 18h47m | 18h49m | 6h19m | 0.09 |
| 2024-12-04 | 6h20m | 6h55m | 18h11m | 18h47m | 20h00m | 6h20m | 0.16 |
| 2024-12-05 | 6h21m | 6h56m | 18h11m | 18h47m | 21h15m | 6h21m | 0.24 |
| 2024-12-06 | 6h22m | 6h57m | 18h11m | 18h47m | 22h31m | 6h22m | 0.34 |
| 2024-12-07 | 6h22m | 6h58m | 18h11m | 18h47m | 23h47m | 6h22m | 0.45 |
| 2024-12-08 | 6h23m | 6h59m | 18h11m | 18h47m | – | 6h23m | 0.57 |
| 2024-12-09 | 6h24m | 6h59m | 18h11m | 18h47m | 1h03m | 6h24m | 0.68 |
| 2024-12-10 | 6h25m | 7h00m | 18h11m | 18h47m | 2h20m | 6h25m | 0.78 |
| 2024-12-11 | 6h26m | 7h01m | 18h12m | 18h47m | 3h39m | 6h26m | 0.87 |
| 2024-12-12 | 6h26m | 7h02m | 18h12m | 18h47m | 5h01m | 6h26m | 0.94 |
| 2024-12-13 | 6h27m | 7h02m | 18h12m | 18h47m | 6h24m | 6h27m | 0.98 |
| 2024-12-14 | 6h28m | 7h03m | 18h12m | 18h48m | – | – | 1.00 |
| 2024-12-15 | 6h28m | 7h04m | 18h12m | 18h48m | – | – | 0.99 |
| 2024-12-16 | 6h29m | 7h05m | 18h13m | 18h48m | – | – | 0.96 |
| 2024-12-17 | 6h30m | 7h05m | 18h13m | 18h49m | 18h49m | 19h23m | 0.90 |
| 2024-12-18 | 6h30m | 7h06m | 18h13m | 18h49m | 18h49m | 20h37m | 0.83 |
| 2024-12-19 | 6h31m | 7h06m | 18h14m | 18h49m | 18h49m | 21h48m | 0.75 |
| 2024-12-20 | 6h31m | 7h07m | 18h14m | 18h50m | 18h50m | 22h55m | 0.66 |
| 2024-12-21 | 6h32m | 7h07m | 18h15m | 18h50m | 18h50m | 0h00m | 0.57 |
| 2024-12-22 | 6h32m | 7h08m | 18h15m | 18h51m | 18h51m | – | 0.47 |
| 2024-12-23 | 6h33m | 7h08m | 18h16m | 18h51m | 18h51m | 1h03m | 0.38 |
| 2024-12-24 | 6h33m | 7h09m | 18h17m | 18h52m | 18h52m | 2h06m | 0.29 |
| 2024-12-25 | 6h34m | 7h09m | 18h17m | 18h53m | 18h53m | 3h10m | 0.21 |
| 2024-12-26 | 6h34m | 7h09m | 18h18m | 18h53m | 18h53m | 4h16m | 0.14 |
| 2024-12-27 | 6h34m | 7h10m | 18h18m | 18h54m | 18h54m | 5h24m | 0.08 |
| 2024-12-28 | 6h34m | 7h10m | 18h19m | 18h55m | 18h55m | 6h33m | 0.03 |
| 2024-12-29 | 6h35m | 7h10m | 18h20m | 18h55m | 18h55m | 6h35m | 0.01 |
| 2024-12-30 | 6h35m | 7h10m | 18h21m | 19h00m | 19h00m | 6h35m | 0.00 |
| 2024-12-31 | 6h35m | 7h11m | 18h21m | 19h01m | 19h01m | 6h35m | 0.02 |
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 Su Venus: 43.6° E
1 Su 1:21 am New Moon
2 Mo 5:31 pm Moon South Dec.: 28.5° S
3 Tu 7:08 am Mars-Beehive: 1.6° N
4 We 5:40 pm Moon-Venus: 2.4° N
5 Th 9:11 pm Mercury Inferior Conj.
7 Sa 3:19 pm Jupiter Opposition
8 Su 3:49 am Moon-Saturn: .3° S
8 Su 10:27 am First Quarter
9 Mo 2:36 pm Moon Ascending Node
12 Th 8:18 am Moon Perigee: 365400 km
13 Fr 12:13 pm Moon-Pleiades: .1° S
13 Fr 8:12 pm Geminid Shower: ZHR = 120
15 Su 4:02 am Full Moon
15 Su 3:12 pm Moon North Dec.: 28.4° N
17 Tu 7:12 am Moon-Pollux: 2.1° N
18 We 3:46 am Moon-Mars: 1° S
18 We 6:28 am Moon-Beehive: 2.8° S
20 Fr 12:37 am Moon-Regulus: 2.6° S
21 Sa 4:20 am Winter Solstice
22 Su 5:00 am Ursid Shower: ZHR = 10
22 Su 5:18 pm Last Quarter
22 Su 6:21 pm Moon Descending Node
23 Mo 4:39 pm Mercury-Antares: 6.8° N
24 Tu 2:25 am Moon Apogee: 404500 km
24 Tu 2:28 pm Moon-Spica: .2° S
24 Tu 8:59 pm Mercury Elongation: 22° W
28 Sa 9:37 am Moon-Antares: .1° N
30 Mo 12:06 am Moon South Dec.: 28.4° S
30 Mo 5:27 pm New Moon
Jan 1 We Venus: 47° E
Generated using my LookingUp for DOS program.
Sun and Moon Rising and Setting Events
LU Ephemeris of Sky Events for Interlochen/TC
December, 2024 Local time zone: EST
+-----------------------------------------------------------------------+
| DATE | SUN SUN DAYLIGHT| TWILIGHT* |MOON RISE OR ILLUM |
| | RISE SET HOURS | END START |PHASE SET** TIME FRACTN|
+=======================================================================+
|Sun 1| 08:00a 05:03p 09:02 | 06:12p 06:51a |New Set 04:56p 1%|
|Mon 2| 08:01a 05:03p 09:01 | 06:12p 06:52a | Set 05:47p 3%|
|Tue 3| 08:02a 05:02p 09:00 | 06:12p 06:53a | Set 06:48p 8%|
|Wed 4| 08:03a 05:02p 08:58 | 06:12p 06:54a | Set 07:59p 14%|
|Thu 5| 08:04a 05:02p 08:57 | 06:12p 06:54a | Set 09:14p 23%|
|Fri 6| 08:05a 05:02p 08:56 | 06:12p 06:55a | Set 10:31p 32%|
|Sat 7| 08:06a 05:02p 08:55 | 06:12p 06:56a | Set 11:47p 43%|
+------+-----------------------+----------------+-----------------------+
|Sun 8| 08:07a 05:02p 08:54 | 06:12p 06:57a |F Qtr Set 01:03a 54%|
|Mon 9| 08:08a 05:02p 08:53 | 06:12p 06:58a | Set 02:20a 65%|
|Tue 10| 08:09a 05:02p 08:52 | 06:12p 06:59a | Set 03:39a 76%|
|Wed 11| 08:10a 05:02p 08:51 | 06:12p 07:00a | Set 05:00a 85%|
|Thu 12| 08:11a 05:02p 08:51 | 06:12p 07:00a | Set 06:24a 92%|
|Fri 13| 08:12a 05:02p 08:50 | 06:13p 07:01a | Set 07:45a 97%|
|Sat 14| 08:12a 05:02p 08:49 | 06:13p 07:02a | Set 08:57a 100%|
+------+-----------------------+----------------+-----------------------+
|Sun 15| 08:13a 05:02p 08:49 | 06:13p 07:02a |Full Rise 05:01p 99%|
|Mon 16| 08:14a 05:03p 08:48 | 06:13p 07:03a | Rise 06:09p 96%|
|Tue 17| 08:14a 05:03p 08:48 | 06:14p 07:04a | Rise 07:23p 92%|
|Wed 18| 08:15a 05:03p 08:48 | 06:14p 07:04a | Rise 08:36p 85%|
|Thu 19| 08:16a 05:04p 08:48 | 06:15p 07:05a | Rise 09:47p 77%|
|Fri 20| 08:16a 05:04p 08:48 | 06:15p 07:05a | Rise 10:55p 68%|
|Sat 21| 08:17a 05:05p 08:48 | 06:16p 07:06a | Rise 11:59p 59%|
+------+-----------------------+----------------+-----------------------+
|Sun 22| 08:17a 05:05p 08:48 | 06:16p 07:06a |L Qtr Rise 01:02a 49%|
|Mon 23| 08:18a 05:06p 08:48 | 06:17p 07:07a | Rise 02:05a 40%|
|Tue 24| 08:18a 05:07p 08:48 | 06:17p 07:07a | Rise 03:10a 31%|
|Wed 25| 08:18a 05:07p 08:48 | 06:18p 07:08a | Rise 04:16a 23%|
|Thu 26| 08:19a 05:08p 08:49 | 06:19p 07:08a | Rise 05:24a 15%|
|Fri 27| 08:19a 05:09p 08:49 | 06:19p 07:08a | Rise 06:32a 9%|
|Sat 28| 08:19a 05:09p 08:50 | 06:20p 07:09a | Rise 07:38a 4%|
+------+-----------------------+----------------+-----------------------+
|Sun 29| 08:19a 05:10p 08:50 | 06:21p 07:09a | Rise 08:36a 1%|
|Mon 30| 08:19a 05:11p 08:51 | 06:21p 07:09a |New Set 04:37p 0%|
|Tue 31| 08:20a 05:12p 08:52 | 06:22p 07:09a | Set 05:46p 1%|
+-----------------------------------------------------------------------+
* Nautical Twilight
** Moonrise or moonset, whichever occurs between sunset and sunrise
Generated using my LookingUp for DOS program.
Ephemeris: 11/27/2024 – Checking up on the naked-eye planets this week
This is Ephemeris for Wednesday, November 27th. Today the Sun will be up for 9 hours and 9 minutes, setting at 5:05, and it will rise tomorrow at 7:57. The Moon, 4 days before new, will rise at 5:23 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. Venus can be spotted low in the south-southwestern sky by 5:30 PM, about 25 minutes after sunset. It will set at 7:52. Saturn will be in the south-southeast at 6 PM. Jupiter will rise at 5:45 PM in the east northeast, and be a good object for the small telescope about an hour later. Mars, rises tonight near 9:16, Both Mars and Jupiter are considered morning planets, since they are still up at sunrise. By 6 AM tomorrow Jupiter will be in the west, above and right of Orion, while reddish Mars will be high in the southwest. Jupiter and Saturn are good planets to view with a small telescope, Mars will appear only a quarter the diameter of Jupiter.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 11/26/2024 – Finding the celestial charioteer and his goats
This is Ephemeris for Tuesday, 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, 4 days past last quarter, will rise at 4:18 tomorrow morning.
The constellation Auriga the charioteer is halfway up the sky in the east northeast at 9 p.m. It is a pentagon of stars, with the brilliant star Capella at the upper left of its corners. Capella represents a mama goat he’s carrying. A narrow triangle of stars just right of Capella are her kids, that is her baby goats. The Kids is an informal constellation or asterism. The Milky Way runs through Auriga, but it’s not very bright here. We are looking away from the center of the Milky Way to the more sparse outer parts of our galaxy. Within and near that pentagon, one can sweep with binoculars and low power telescopes to find several star clusters, groups of hundreds of stars born in the clump we still see them in. These star clusters will appear as fuzzy spots in binoculars.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
