Archive
Ephemeris: 10/23/2023 – Venus is at its greatest separation from the Sun in the morning
This is Ephemeris for Monday, October 23rd. Today the Sun will be up for 10 hours and 36 minutes, setting at 6:45, and it will rise tomorrow at 8:09. The Moon, 2 days past first quarter, will set at 2:36 tomorrow morning.
Our brilliant morning planet Venus will reach its greatest apparent angle from the Sun later today. It’s called the greatest western elongation because it’s west of the Sun and rises before the Sun. From now until its superior conjunction next year, on June 4th. It will move closer and closer to the Sun from our vantage point. But it’s just moving around behind the Sun. The Mayans at the peak of their civilization were diligent observers of Venus. They found the Venus cycle, what we would call synodic period of Venus of 584 days, from the heliacal rising of Venus, its first appearance in the morning sky after disappearing in the evening, to the next heliacal rising. Venus would reach its greatest elongation from the Sun about 66 days after its heliacal rising.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Ephemeris: 10/20/2023 – Halley’s Comet is back! Sort of.
This is Ephemeris for Friday, October 20th. Today the Sun will be up for 10 hours and 45 minutes, setting at 6:50, and it will rise tomorrow at 8:05. The Moon, 1 day before first quarter, will set at 10:42 this evening.
Halley’s Comet is back! (Pronounced Hall-ey’s) Well sorta. In the form of the Orionid meteor shower. Bits of Halley’s Comet from previous passes by the Earth’s orbit make their twice-yearly show in our skies as these bits collide with the Earth’s atmosphere. Halley’s orbit passes close to the earth’s orbit at points where the Earth is around May 6th and again near October 21st. Light dust and ionized gas get blown back into the tail of the comet. Heavier particles, still affected by the pressure of sunlight and the gravitational pull of the Sun and planets end up roughly following the comet’s orbit. In the morning after the Moon sets (11:55 pm on the 21st) should be the best time to see them. They will seem to come from a spot above Orion and below Gemini.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Ephemeris: 10/18/2023 – Where have the naked-eye planets wandered off to this week
This is Ephemeris for Wednesday, October 18th. Today the Sun will be up for 10 hours and 51 minutes, setting at 6:53, and it will rise tomorrow at 8:03. The Moon, 3 days before first quarter, will set at 8:50 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 Mars sets too close to sunset to be seen, and Mercury rises too close to sunrise, and besides it will enter the evening sky after Friday. Saturn is the sole official evening planet visible. It can be spotted in the southeast to south in the evening. And it will still be visible in the morning hours until it sets at 3:17 am. Saturn is seen against the stars of Aquarius this year and next. Jupiter and Venus are the visible morning planets. Jupiter, still a morning planet, will rise at 7:34 pm. It’s in Aries this year. Jupiter has to rise before sunset to be an evening planet. Venus, the brilliant morning star, will rise in the east-northeast at 4:02 am.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Ephemeris: 10/12/2023 – Saturday’s (October 14, 2023) Annular Solar Eclipse
This is Bob Moler with Ephemeris for Thursday, October 12th. Today the Sun will be up for 11 hours and 9 minutes, setting at 7:03, and it will rise tomorrow at 7:55. The Moon, 2 days before new, will rise at 6:39 tomorrow morning.
There will be a partial solar eclipse Saturday for most of the unit for the 48 Continental United States. It will be maximum on a line from Oregon through Texas. It’s called an annular eclipse. At its maximum an annular eclipse is an eclipse where the Moon is too far away to completely cover the face of the Sun so at maximum it leaves a ring of the Sun. Some call it a Ring of Fire. We’re well north of that line so we will see a partial eclipse where about 35% of the Sun will be covered by the Moon at its peak, although the Moon will encroach about 45% of the diameter of the Sun. For northern Michigan the eclipse will start at about 11:42 am, maximum eclipse is about 1 pm and the eclipse will end at 2:18 pm. I’ll talk about eclipse viewing safety tomorrow.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Ephemeris: 10/11/2023 – Where have the naked-eye planets wandered off to this week?
This is Ephemeris for International Day of the Girl, Wednesday, October 11th. Today the Sun will be up for 11 hours and 12 minutes, setting at 7:05, and it will rise tomorrow at 7:54. The Moon, 3 days before new, will rise at 5:35 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 Mars sets too close to sunset to be seen, and Mercury rises too close to sunrise. Saturn is the sole official evening planet visible. It can be spotted in the southeast in the evening. And it will still be visible in the morning hours until it sets at 3:46 am. Saturn is seen against the stars of Aquarius this year and next. Jupiter and Venus are the visible morning planets. Jupiter, still a morning planet, will rise at 8:04 pm. It’s in Ares this year. It has to rise before sunset to be an official evening planet. Venus, the brilliant morning star, will rise in the east-northeast at 3:57 am, and be seen in the east thereafter.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Ephemeris: 10/04/2023 – Let’s find out where the naked-eye planets have wandered off to this week
This is Ephemeris for Wednesday, October 4th. Today the Sun will be up for 11 hours and 33 minutes, setting at 7:18, and it will rise tomorrow at 7:45. The Moon, 2 days before last quarter, will rise at 10:18 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 Mars sets too close to sunset to be seen, and Mercury rises too late. Saturn is the sole evening planet visible. It can be spotted in the southeast in the evening. And it will still be visible most of the morning hours morning until it sets at 4:15 am. Saturn is in retrograde or westward motion now, against the stars of Aquarius, and will continue to do so until November 5th. Jupiter and Venus are the visible morning planets. Jupiter, in Aries, will rise at 8:29 pm. It, like Saturn is in retrograde, which will last the rest of this year. Venus is our brilliant morning star which will rise in the east-northeast at 3:56 am.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Ephemeris: 10/03/2023 – How to find Cassiopeia the queen
This is Bob Moler with Ephemeris for Tuesday, October 3rd. Today the Sun will be up for 11 hours and 36 minutes, setting at 7:19, and it will rise tomorrow at 7:44. The Moon, 3 days before last quarter, will rise at 9:35 this evening.
The stars of the autumn skies are slowly replacing the summer stars from the east. By 9 pm Scorpius the scorpion is gone, The Teapot asterism of Sagittarius is pouring its tea on the southwestern horizon. Looking halfway up in the northeastern sky these autumn the evenings one can find the letter W shaped constellation of Cassiopeia the queen. Cassiopeia is so far north that it never sets for us in Michigan. It is opposite the pole star Polaris from the handle of Big Dipper. Above and left of Cassiopeia is a dim upside down church steeple shaped constellation of Cepheus the king, her husband.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Delta Cephei is the archetype for the important Cepheid variable stars that are used in distance measurement as far as the nearest galaxies. Delta itself varies its brightness from magnitude 4.37 up to 3.48. In astronomy the lower the magnitude the brighter the star. The difference of 0.89 magnitude equals a difference in brightness of 2.27 times. Delta has a pulsation period of 5.367 days. For Cepheids, the longer the period the brighter the star.
Ephemeris: 09/29/2023 – Previewing October skies
This is Ephemeris for Friday, September 29th. Today the Sun will be up for 11 hours and 49 minutes, setting at 7:27, and it will rise tomorrow at 7:39. The Moon today, the full harvest supermoon, will rise at 7:45 this evening.
Let’s look at the skies for the month of October The sun will still be moving south rapidly. Daylight hours in the Interlochen/Traverse City area will drop from 11 hours and 43 minutes Sunday to 10 hours 13 minutes on the 31st. The altitude of the Sun above the southern horizon at local noon will be 42 degrees Sunday, and will descend to 31 degrees on Halloween, also in the Interlochen area. The Straits area will have the Sun a degree lower. Local noon, when the Sun is due south will be about 1:30 p.m. in Interlochen. There will be, for us in Michigan, a partial solar eclipse around midday on Saturday the 14th.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
October Evening Star Chart
The planets and stars are plotted for the 15th at 10 p.m. EDT 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). To duplicate the star positions on a planisphere you may have to set it to 1 hour 45 minutes earlier than the current time.
October Morning Star Chart
or 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.
- Leaky dipper drips on Leo.
- Follow the arc of the handle of the Big Dipper to the star Arcturus.
- The Summer Triangle is in red.
- DracR – Draconid Radiant – Peaks the 8th – Zenithal Hourly Rate < 10 with rare outbursts of a thousand an hour. It’s hindered this year by the full moon.
- OriR – Orionid Radiant – Peak 21st – Zenithal Hourly Rate = 20
Twilight Limits, Nautical and Astronomical
| EDT | |||||||
| Morning | Twilight | Evening | Twilight | Dark | Night | Moon | |
| Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
| 2023-10-01 | 6h08m | 6h43m | 20h30m | 21h04m | – | – | 0.90 |
| 2023-10-02 | 6h10m | 6h44m | 20h28m | 21h02m | – | – | 0.82 |
| 2023-10-03 | 6h11m | 6h45m | 20h26m | 21h00m | 21h00m | 21h35m | 0.73 |
| 2023-10-04 | 6h12m | 6h46m | 20h24m | 20h58m | 20h58m | 22h19m | 0.63 |
| 2023-10-05 | 6h14m | 6h48m | 20h22m | 20h57m | 20h57m | 23h11m | 0.54 |
| 2023-10-06 | 6h15m | 6h49m | 20h21m | 20h55m | 20h55m | – | 0.44 |
| 2023-10-07 | 6h16m | 6h50m | 20h19m | 20h53m | 20h53m | 0h11m | 0.34 |
| 2023-10-08 | 6h17m | 6h51m | 20h17m | 20h51m | 20h51m | 1h15m | 0.26 |
| 2023-10-09 | 6h19m | 6h53m | 20h15m | 20h49m | 20h49m | 2h21m | 0.18 |
| 2023-10-10 | 6h20m | 6h54m | 20h14m | 20h47m | 20h47m | 3h27m | 0.11 |
| 2023-10-11 | 6h21m | 6h55m | 20h12m | 20h46m | 20h46m | 4h32m | 0.06 |
| 2023-10-12 | 6h22m | 6h56m | 20h10m | 20h44m | 20h44m | 5h36m | 0.02 |
| 2023-10-13 | 6h24m | 6h57m | 20h08m | 20h42m | 20h42m | 6h24m | 0.00 |
| 2023-10-14 | 6h25m | 6h59m | 20h07m | 20h40m | 20h40m | 6h25m | 0.00 |
| 2023-10-15 | 6h26m | 7h00m | 20h05m | 20h39m | 20h39m | 6h26m | 0.02 |
| 2023-10-16 | 6h27m | 7h01m | 20h03m | 20h37m | 20h37m | 6h27m | 0.06 |
| 2023-10-17 | 6h29m | 7h02m | 20h02m | 20h35m | 20h35m | 6h29m | 0.12 |
| 2023-10-18 | 6h30m | 7h04m | 20h00m | 20h34m | 20h50m | 6h30m | 0.20 |
| 2023-10-19 | 6h31m | 7h05m | 19h58m | 20h32m | 21h40m | 6h31m | 0.29 |
| 2023-10-20 | 6h32m | 7h06m | 19h57m | 20h31m | 22h42m | 6h32m | 0.40 |
| 2023-10-21 | 6h34m | 7h07m | 19h55m | 20h29m | 23h56m | 6h34m | 0.51 |
| 2023-10-22 | 6h35m | 7h08m | 19h54m | 20h28m | – | 6h35m | 0.62 |
| 2023-10-23 | 6h36m | 7h10m | 19h52m | 20h26m | 1h15m | 6h36m | 0.73 |
| 2023-10-24 | 6h37m | 7h11m | 19h51m | 20h25m | 2h37m | 6h37m | 0.83 |
| 2023-10-25 | 6h38m | 7h12m | 19h49m | 20h23m | 3h57m | 6h38m | 0.91 |
| 2023-10-26 | 6h40m | 7h13m | 19h48m | 20h22m | 5h17m | 6h40m | 0.96 |
| 2023-10-27 | 6h41m | 7h15m | 19h47m | 20h20m | 6h36m | 6h41m | 0.99 |
| 2023-10-28 | 6h42m | 7h16m | 19h45m | 20h19m | – | – | 1.00 |
| 2023-10-29 | 6h43m | 7h17m | 19h44m | 20h18m | – | – | 0.98 |
| 2023-10-30 | 6h44m | 7h18m | 19h42m | 20h16m | – | – | 0.93 |
| 2023-10-31 | 6h46m | 7h19m | 19h41m | 20h15m | – | – | 0.87 |
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
NASA - SKYCAL - Sky Events Calendar 2023
Date Time Event
Oct 1 Su Venus: 44.2° W
1 Su 11:16 pm Moon-Jupiter: 3.5° S
3 Tu 12:25 am Moon-Pleiades: 1.1° N
5 Th 4:31 pm Moon North Dec.: 28.3° N
6 Fr 9:48 am Last Quarter
7 Sa 6:23 am Moon-Pollux: 1.6° N
9 Mo 2:10 am Venus-Regulus: 2.3° S
9 Mo 11:41 pm Moon Apogee: 405,400 km
14 Sa 1:55 pm New Moon
14 Sa 2:00 pm Annular Solar Eclipse
11:42 am - 2:18 pm in the Grand Traverse area
14 Sa 9:11 pm Moon Descending Node
18 We 9:17 am Moon-Antares: 0.9° S
20 Fr 1:08 am Mercury Superior Conj.
20 Fr 5:19 am Moon South Dec.: 28.3° S
21 Sa 7:48 pm Orionid Meteor Shower: ZHR = 20
21 Sa 11:29 pm First Quarter
23 Mo 5:59 pm Venus Greatest Western Elongation: 46.4° W
24 Tu 3:52 am Moon-Saturn: 2.8° N
25 We 10:53 pm Moon Perigee: 364,900 km
27 Fr 11:14 pm Moon Ascending Node
28 Sa 4:14 pm Partial Lunar Eclipse
Visible: e Americas, Europe, Africa, Asia, Australia
28 Sa 4:24 pm Full Hunter's Moon
29 Su 4:10 am Moon-Jupiter: 3.2° S
30 Mo 9:30 am Moon-Pleiades: 1.1° N
Nov 1 We Venus: 46.2° W
All event times are given for UTC-4 hr: Eastern Daylight Saving 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 October, 2023 Local time zone: EDT +-----------------------------------------------------------------------+ | DATE | SUN SUN DAYLIGHT| TWILIGHT* |MOON RISE OR ILLUM | | | RISE SET HOURS | END START |PHASE SET** TIME FRACTN| +=======================================================================+ |Sun 1| 07:40a 07:23p 11:43 | 08:26p 06:37a | Rise 08:31p 91%| |Mon 2| 07:41a 07:21p 11:40 | 08:24p 06:38a | Rise 09:00p 84%| |Tue 3| 07:42a 07:19p 11:36 | 08:22p 06:39a | Rise 09:35p 75%| |Wed 4| 07:44a 07:18p 11:33 | 08:20p 06:41a | Rise 10:18p 65%| |Thu 5| 07:45a 07:16p 11:30 | 08:19p 06:42a | Rise 11:11p 56%| |Fri 6| 07:46a 07:14p 11:27 | 08:17p 06:43a |L Qtr Rise 12:10a 46%| |Sat 7| 07:47a 07:12p 11:24 | 08:15p 06:44a | Rise 01:15a 36%| +------+-----------------------+----------------+-----------------------+ |Sun 8| 07:49a 07:10p 11:21 | 08:13p 06:46a | Rise 02:21a 28%| |Mon 9| 07:50a 07:09p 11:18 | 08:11p 06:47a | Rise 03:26a 20%| |Tue 10| 07:51a 07:07p 11:15 | 08:10p 06:48a | Rise 04:31a 13%| |Wed 11| 07:52a 07:05p 11:12 | 08:08p 06:49a | Rise 05:35a 7%| |Thu 12| 07:54a 07:03p 11:09 | 08:06p 06:51a | Rise 06:39a 3%| |Fri 13| 07:55a 07:01p 11:06 | 08:05p 06:52a | Rise 07:45a 1%| |Sat 14| 07:56a 07:00p 11:03 | 08:03p 06:53a |New Set 07:00p 0%| +------+-----------------------+----------------+-----------------------+ |Sun 15| 07:58a 06:58p 11:00 | 08:01p 06:54a | Set 07:20p 2%| |Mon 16| 07:59a 06:56p 10:57 | 08:00p 06:55a | Set 07:43p 5%| |Tue 17| 08:00a 06:55p 10:54 | 07:58p 06:57a | Set 08:12p 11%| |Wed 18| 08:01a 06:53p 10:51 | 07:56p 06:58a | Set 08:50p 18%| |Thu 19| 08:03a 06:51p 10:48 | 07:55p 06:59a | Set 09:39p 27%| |Fri 20| 08:04a 06:50p 10:45 | 07:53p 07:00a | Set 10:42p 37%| |Sat 21| 08:05a 06:48p 10:42 | 07:52p 07:02a |F Qtr Set 11:55p 48%| +------+-----------------------+----------------+-----------------------+ |Sun 22| 08:07a 06:46p 10:39 | 07:50p 07:03a | Set 01:15a 60%| |Mon 23| 08:08a 06:45p 10:36 | 07:49p 07:04a | Set 02:36a 71%| |Tue 24| 08:09a 06:43p 10:33 | 07:47p 07:05a | Set 03:57a 81%| |Wed 25| 08:11a 06:42p 10:30 | 07:46p 07:06a | Set 05:16a 89%| |Thu 26| 08:12a 06:40p 10:28 | 07:44p 07:08a | Set 06:36a 95%| |Fri 27| 08:13a 06:38p 10:25 | 07:43p 07:09a | Set 07:55a 99%| |Sat 28| 08:15a 06:37p 10:22 | 07:41p 07:10a |Full Rise 06:30p 100%| +------+-----------------------+----------------+-----------------------+ |Sun 29| 08:16a 06:36p 10:19 | 07:40p 07:11a | Rise 06:56p 98%| |Mon 30| 08:17a 06:34p 10:16 | 07:39p 07:13a | Rise 07:29p 94%| |Tue 31| 08:19a 06:33p 10:13 | 07:37p 07:14a | Rise 08:09p 88%| +-----------------------------------------------------------------------+ * Nautical Twilight ** Moonrise or moonset, whichever occurs between sunrise and sunset
Generated using my LookingUp for DOS program.
Ephemeris: 09/28/2023 – Tomorrow night’s full moon is the Harvest Moon
This is Ephemeris for Thursday, September 28th. Today the Sun will be up for 11 hours and 52 minutes, setting at 7:29, and it will rise tomorrow at 7:38. The Moon, 1 day before full, will set at 7:43 tomorrow morning.
Tomorrow night’s full moon is the Harvest Moon. It is the most famous of the named full moons, and was very useful in the days before electric lights. The reason is that the Moon, around the time it is full, doesn’t advance its rising time very much from night to night, effectively adding its light to twilight to allow more time to gather in crops. This is because the Moon is moving north as well as eastward. The farther north it is, the longer it stays up and retards the advance in rise times. On average, the Moon rises 50 minutes later each night. This week, the interval is down near 22 minutes advance in moonrise times per day, extending twilight and the amount of time each day to harvest the crops for a few more days.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
My interest in the Harvest Moon is not in harvesting the crops. I just have a little garden, so it doesn’t take that long to pick tomatoes or whatever. But as an amateur astronomer I’m more interested in deep sky objects than I am in planets. Deep sky objects or DSOs are objects beyond the solar system and are usually very dim, which requires dark skies to view them. Near the Harvest Moon and even in August near the full moon it takes nearly a week for that @#$%^&* Moon to get the heck out of the evening sky, so I don’t have to stay up till after midnight to see anything. That’s I why have this interest in the Harvest Moon. Know your enemy!
Ephemeris: 09/27/2023 – Let’s find out where the naked-eye planets have wandered off to this week
This is Bob Moler with Ephemeris for Wednesday, September 27th. Today the Sun will be up for 11 hours and 55 minutes, setting at 7:31, and it will rise tomorrow at 7:36. The Moon, 2 days before full, will set at 6:22 tomorrow morning.
Let’s find out where the naked-eye planets have wandered off to this week. Four of those five planets are now visible, but Mars is too close to the Sun to be seen. Saturn is the sole evening planet visible. It can be spotted in the southeast in the evening. And it will still be visible throughout the morning hours until it sets at 4:44 am. Saturn is in retrograde or westward motion now, against the stars of Aquarius. Jupiter, Venus and Mercury are the morning planets. Jupiter will rise at 9:02 pm. It, like Saturn is moving retrograde, which will last the rest of this year. Venus is our brilliant morning star, at its brightest, and will rise in the east-northeast at 3:59 am. Tiny Mercury will rise at 6:10 am, and be visible in the east by around 6:30.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Bob Moler's Ephemeris Blog 