Ephemeris: 12/16/2025 – Finding Orion and the Wintermaker
This is Ephemeris for Tuesday, December 16th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:03, and it will rise tomorrow at 8:14. The Moon, 3 days before new, will rise at 6:19 tomorrow morning.
In the east, the central winter constellation Orion the hunter throws a leg over the horizon around 7 PM as Robert Frost told in his poem Star-Splitter. The upright rectangle that is his body is tilted to the left as he rises on December evenings. A bright red star, Betelgeuse, is 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 Anishinaabe 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, five days from now.
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; EST, UT – 5 hours) unless stated otherwise. Times will be different for other locations.
Addendum
Ephemeris: 12/15/2025 – Capella, the winter star that never quite leaves us*
This is Ephemeris for Monday, December 15th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:02, and it will rise tomorrow at 8:14. The Moon, halfway from last quarter to new, will rise at 5:13 tomorrow morning.
Capella is the northernmost first magnitude stars. Tonight it shines in the northeastern sky. First magnitude stars are the 21 brightest stars in the night sky. Capella is the 6th brightest. Although I’ve always known it as the little she-goat, Capella’s name literally translates to “little goat.” Her three Kids are represented by a narrow triangle of stars positioned to the right of her in tonight’s evening sky. Capella is in the topmost corner of the pentagonal constellation of Auriga the Charioteer. Capella is actually a system of four stars only 43 light years away. And never sets for listeners in the Interlochen Public Radio transmission area who have a low northern horizon.
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; EST, UT – 5 hours) unless stated otherwise. Times will be different for other locations.
* If you live north of 44° north latitude.
Addendum
Ephemeris: 12/12/2025 – The most active meteor shower of the year will peak Sunday morning
This is Ephemeris for Friday, December 12th. Today the Sun will be up for 8 hours and 51 minutes, setting at 5:02, and it will rise tomorrow at 8:11. The Moon, 1 day past last quarter, will rise at 1:58 tomorrow morning.
We are ramping up to the most active meteor shower of the year, the Geminid meteor shower. And it has been getting more active over the years. The peak will be about 2 AM Sunday morning with a 30% Moon rising shortly after 3. The radiant is the point in space where the meteors seem to come from, which is near the star Castor in the constellation Gemini from which the shower gets its name. Unlike most meteor showers, the Geminids will be visible all night. The meteors will be seen all over the sky, but they all can be traced back to the radiant. The body responsible for this meteor shower is an asteroid rather than a comet with the name 3200 Phaethon, which comes very close to the Sun.
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; EST, UT – 5 hours) unless stated otherwise. Times will be different for other locations.
Addendum
Ephemeris: 12/11/25 – The constellation of the guy with the goats
This is Ephemeris for Thursday, December 11th. Today the Sun will be up for 8 hours and 51 minutes, setting at 5:02, and it will rise tomorrow at 8:11. The Moon, at last quarter today, will rise at 12:53 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 shown without his chariot. Ptolemy, last of the great Greek astronomers called Auriga the coachman. If so, he did have room for the goats.
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: 12/10/2025 – Taking a look at the whereabouts of the naked-eye planets
This is Ephemeris for Wednesday, 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, 1 day before last quarter, will rise at 11:45 this evening.
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, half a degree from being edge on and slowly opening. 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 7:29 PM in the east-northeast, beneath Castor and Pollux, the bright stars of Gemini. Jupiter’s 4 brightest moons can be seen even in binoculars, and shift position night to night. Tonight they will all be in line on one side of the planet. Mercury might be spotted very low in the east-southeast by 7 AM tomorrow morning.
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: 12/09/2025 – 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
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