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Ephemeris: 01/12/2026 – How to find the twins of Gemini
This is Ephemeris for Monday, January 12th. Today the Sun will be up for 9 hours and 6 minutes, setting at 5:24, and it will rise tomorrow at 8:17. The Moon, 2 days past last quarter, will rise at 4:08 tomorrow morning.
Another famous winter constellation is Gemini. The constellation of Gemini the Twins is visible halfway to the zenith in the east, at the top and left of Orion the hunter, at 9 pm. The namesake stars of the two lads, are the two bright stars at the left end of Gemini, and are high and are due east. Castor is on top, while Pollux is below. From them come two lines of stars that outline the two, extending horizontally toward Orion. Currently, Jupiter in its retrograde motion is situated level with Pollux at 9 PM. Pollux is left of the much brighter Jupiter. In Greek mythology the Gemini twins were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in 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; EST, UT – 5 hours) unless stated otherwise. Times will be different for other locations.
Addendum
Ephemeris: 01/27/2025 – Gemini the twins with Mars this year
This is Ephemeris for Monday, January 27th. Today the Sun will be up for 9 hours and 38 minutes, setting at 5:44, and it will rise tomorrow at 8:05. The Moon, 2 days before new, will rise at 8:00 tomorrow morning.
Another famous winter constellation is Gemini. The constellation of Gemini the Twins is visible halfway to the zenith in the east, at the top and left of Orion the hunter, at 9 pm. The namesake stars of the two lads, are the two bright stars at the left end of Gemini, and are high and are due east. Castor is on top, while Pollux is below. From them come two lines of stars that outline the two, extending horizontally toward Orion. Mars is passing in front of the stars of Gemini during the first quarter of this year, reaching the western end of its retrograde loop and doubling back to the east. In Greek mythology the Gemini twins were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the sky.
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: 03/12/24 – The story of the twins of Gemini
This is Bob Moler with Ephemeris for Tuesday, March 12th. Today the Sun will be up for 11 hours and 46 minutes, setting at 7:45, and it will rise tomorrow at 7:57. The Moon, 2 days past new, will set at 11:07 this evening.
A week ago I talked about how to find the constellation of Gemini the twins above and to the left of the constellation Orion. Today I’ll talk about their story. Gemini the twins are fraternal twins, Castor and Pollux. Their namesake stars are the brightest in Gemini, with Castor above and the brighter Pollux below and left. Pollux was fathered by the god Zeus who raped his mother in the Leda and the Swan incident, while Castor was fathered by a mortal. They both went on the quest for the Golden Fleece with Jason and the Argonauts. Unfortunately Castor was killed. Pollux loved his brother so much he petitioned Zeus for him to die also and join Castor in the underworld. Instead, Zeus placed them both in the sky where we see them as 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: 03/05/2024 – Finding Gemini the twins
This is Ephemeris for Tuesday, March 5th. Today the Sun will be up for 11 hours and 24 minutes, setting at 6:36, and it will rise tomorrow at 7:10. The Moon, 2 days past last quarter, will rise at 5:22 tomorrow morning.
The constellation of Gemini the twins can be seen high in the south at 8 pm tonight. It’s located above and left of the constellation of Orion. The two brightest stars at the upper left of the constellation have the twin’s names. They are Castor, the one to the upper right and Pollux the brighter one to the lower left. I tend to see the constellation as the two lines of stars from Castor and Pollux running down toward Orion as a silhouette of these two boys standing together. Others see them as two stick figures. At the bottom of the line of stars emanating from Castor, what I consider Castor’s foot, is a lovely star cluster which is visible in binoculars as a little fuzzy spot, but a telescope will show a great number of stars here called Messier 35 or simply M35.
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
04/18/2023 – Ephemeris – Orion rotates 90 degrees from rising to setting
This is Bob Moler with Ephemeris for Tuesday, April 18th. Today the Sun will be up for 13 hours and 37 minutes, setting at 8:31, and it will rise tomorrow at 6:52. The Moon, 2 days before new, will rise at 6:43 tomorrow morning.
As the constellation of Orion the hunter, that dominated our winter skies, moves into the west in the evening, it will have rotated 90 degrees from its rising orientation. As we saw it rising last November, its three belt stars were nearly vertically aligned. Now, as Orion nears the western horizon, those belt stars have rotated to be almost horizontal. The same is true of Gemini’s two brightest stars, Castor and Pollux. They are the two stars above red Mars, which is now halfway through Gemini on its eastward travels. Orion, a minor Greek hero, is most famous for how he died. I know of three versions, all different. The one that fits Orion’s current setting is that he was killed by the sting of a giant scorpion. So he must flee the sky before Scorpius the scorpion rises, which is around midnight tonight.
This amount of rotation between rising and setting is only true for latitudes near 45 degrees north or south, such as Northern Michigan, and objects near the celestial equator. The rotation for other latitudes would be 2 x (90 – latitude) for equatorial celestial objects. The name given for the term (90 – latitude) is colatitude. 90 degrees is the latitude of the Earth’s poles.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –4 hours). They may be different for your location.
Addendum
When Orion is rising, its belt stars are nearly vertically aligned. Castor and Pollux, too, appear nearly vertically aligned. This was for November 30, 2022, at 9 pm. Mars was near opposition then and quite close to the Earth, so it had shown quite brightly. Created using Stellarium and LibreOffice Draw.
Orion’s belt stars show that the constellation has rotated about 90 degrees from their rising orientation. This is for 10 pm, April 18, 2023. Note that Venus is the Evening Star now, and Mars is much dimmer, as the Earth has moved ahead and away from it. Created using Stellarium and LibreOffice Draw, for the added labels.
01/20/2023 – Ephemeris – Gemini’s Castor is six stars orbiting each other
This is Ephemeris for Friday, January 20th. Today the Sun will be up for 9 hours and 21 minutes, setting at 5:34, and it will rise tomorrow at 8:12. The Moon, 1 day before new, will rise at 8:34 tomorrow morning.
At 9 p.m. the constellation of Gemini the twins will be seen high in the east-southeast. The namesake stars of the two lads are the two bright stars at the left of the constellation. Pollux the pugilist, or boxer, is the lower and slightly brighter of the two, while Castor, the horseman, is the other star, or rather a six-star system. In telescopes two close stars may be seen, each is a spectroscopic binary, meaning the lines of two stars can be seen in the spectrum, shifting as they orbit each other. Another faint spectroscopic binary also belongs. Pollux, though a single star, does have at least one planet with over twice the mass of Jupiter orbiting the star. Pollux and Castor are respectively 34 and 50 light years away. Not too far away as stars go.
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
01/19/2023 – Ephemeris – Gemini, twins with a secret
This is Ephemeris for Thursday, January 19th. Today the Sun will be up for 9 hours and 19 minutes, setting at 5:33, and it will rise tomorrow at 8:13. The Moon, 2 days before new, will rise at 7:38 tomorrow morning.
Another famous winter constellation is Gemini. The constellation of Gemini the Twins is visible halfway to the zenith in the east, at the top and left of Orion the hunter, at 9 pm. The namesake stars of the two lads, are the two bright stars at the left end of Gemini, and are high and are due east. Castor is on top, while Pollux is below. From them come two lines of stars that outline the two, extending horizontally toward Orion. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the 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
Gemini finder animation for the second half of January 2023. It’s dated because Mars is dawdling in Taurus near the Pleiades. Mars is now back to heading eastward once again, after being in retrograde or westward motion as the Earth passed it in early December. Mars will officially enter Gemini in March. Created using Stellarium, and GIMP.
03/03/2022 – Ephemeris – Finding Cancer the crab
This is Ephemeris for Thursday, March 3rd. Today the Sun will be up for 11 hours and 16 minutes, setting at 6:33, and it will rise tomorrow at 7:15. The Moon, 1 day past new, will set at 7:46 this evening.
The constellation of Cancer the crab is made of dim stars, which are generally connected, in constellation charts, with lines that make either the letter K or an upside down Y, which lie directly between the star pair Castor and Pollux in Gemini and Regulus in Leo. In the center of the constellation is, what to the naked-eye is a fuzzy spot called Praesepe, or the manger. The two nearby stars, one to the northeast, and one to the southeast are Asellus Borealis, and Asellus Australis, the northern and southern donkey colts feeding out of the manger. Viewing that fuzzy spot with a pair of binoculars will reveal that it’s not fuzzy at all. It resolves into a cluster of stars, which astronomers, over the years, have called the Beehive cluster. Back in the first and second century CE, the Sun entered Cancer to begin the season of summer. It’s now just a transitional constellation between the winter and spring evening skies.
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
Cancer, the crab finder chart. Note the beehive cluster, also known to amateur astronomers as M44, along with other catalog names. Prior to the invention of the telescope this cluster was known as Praesepe which means “Manger”. Click on the image to enlarge it. Created using Stellarium and GIMP.
A closer look at Cancer, noting the donkey stars Asellus Borealis and Australis feeding at the manger, Praesepe or M44, aka: the Beehive Cluster. Created using Cartes du Ciel (Sky Charts) and LibreOffice for captions. Adapted from a chart I created for the March 2022 issue of the GTAS newsletter, the Stellar Sentinel.
01/27/2022 – Ephemeris – Looking at the constellation of Gemini the twins
This is Ephemeris for Thursday, January 27th. Today the Sun will be up for 9 hours and 37 minutes, setting at 5:44, and it will rise tomorrow at 8:06. The Moon, 2 days past last quarter, will rise at 4:56 tomorrow morning.
Another famous winter constellation is Gemini. The constellation of Gemini the Twins is visible high in the southeast, above and left of Orion the hunter, at 9 p.m. The namesake stars of the two lads, are the two bright stars at the left end of Gemini, and are high and nearly in the east. Castor is on top, while Pollux is below. From them come two lines of stars that outline the two, extending horizontally toward Orion. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the 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
Gemini finder animation for 9 pm January 27th, showing just stars, constellation lines and star names, and figures of the lads. Click on the image to enlarge it. Created using Stellarium and GIMP.
02/08/2021 – Ephemeris – A look at Gemini the twins
This is Ephemeris for Monday, February 8th. Today the Sun will be up for 10 hours and 9 minutes, setting at 6:01, and it will rise tomorrow at 7:51. The Moon, 3 days before new, will rise at 6:49 tomorrow morning.
Let’s look at another of the winter constellations, and a member of the Zodiac. The constellation of Gemini the Twins is visible high in the southeast, above and left of Orion the hunter at 9 p.m. The namesake stars of the two lads, will be at the left end of Gemini, are nearly overhead and vertically aligned. Castor is on top, while the slightly brighter Pollux is below. From them come two lines of stars that outline the two extending toward Orion. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the sky, so they could be together forever.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Gemini finder animation for early February at 9 pm (about 3 hours after sunset). Created using Stellarium and GIMP.
Bob Moler's Ephemeris Blog 