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03/12/2020 – Ephemeris – The mythology behind the constellation of Gemini
Ephemeris for Thursday, 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, 3 days past full, will rise at 11:45 this evening.
Lets look at the next to last of the winter constellations, and member of the Zodiac. The constellation 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, nearly vertically aligned. Castor is above, Pollux below. From them can be traced two lines of stars extending toward Orion that outline the two. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus in the famous Leda and the swan affair and immortal, 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 he 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 looking south-southeast around 9 p.m. March 10th, 2020. Created using Stellarium.
Castor and Pollux namesakes of the twins of Gemini in its position around 9 p.m. EDT March 12th. Created using Stellarium.
02/11/2019 – Ephemeris – The stars Castor and Pollux
Ephemeris for Monday, February 11th. Today the Sun will be up for 10 hours and 16 minutes, setting at 6:05, and it will rise tomorrow at 7:47. The Moon, 1 day before first quarter, will set at 12:57 tomorrow morning.
At 9 p.m. the constellation of Gemini the twins will be seen high in the southeast. The namesake stars of the two lads are the two bright stars at the top of the constellation. Pollux the pugilist, or boxer, is the lower 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. A faint nearby spectroscopic binary also belongs. Pollux, though a single star, does have at least one planet, over twice the mass of Jupiter orbiting the star at a distance somewhat greater than Mars is from the Sun. Pollux is 34 light years away while Castor is 50 light years away. Not too far away as stars go.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Gemini with Castor and Pollux. Created with Stellarium.
The Castor star system exploded in this JPL/NASA infographic.
07/14/2017 – Ephemeris – Constellations of the Summer Triangle II: Cygnus the swan
Ephemeris for Friday, July 14th. Today the Sun will be up for 15 hours and 14 minutes, setting at 9:25, and it will rise tomorrow at 6:11. The Moon, 2 days before last quarter, will rise at 12:32 tomorrow morning.
Fairly high in the east at 11 p.m. Is the constellation of Cygnus the swan, flying south through the Milky Way. It is also called the Northern Cross. At the left, the tail of the swan or the head of the cross is the bright star Deneb, one of the stars of the Summer Triangle. The next star right is Sadr the intersection of the body and the wings of the swan seen in flight, or the intersection of the two pieces of the cross. There are two or three stars farther to the right that delineate the swan’s long neck or upright of the cross, that ends with the star Alberio in the beak of the swan or foot of the cross. The crosspiece of the cross extends to the stars on either side of the intersection star Sadr, while the swan’s wings extend to a couple more stars each.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Summer Triangle. Created using Stellarium and The Gimp.
Animated Cygnus finder chart. Created using Stellarium.
In mythology Cygnus was the form Zeus took in the Leda and the swan affair. Out of that union was born Pollux of Gemini fame. His half-brother and twin Castor was fathered by a mere mortal. Go here for their story.
Alberio is the star that shows in Cygnus’ eye. In telescopes of even low power Alberio shows as a binary star whose components are distinctly and beautiful blue and gold. Binoculars are not quite powerful enough to split these two.
Bob Moler's Ephemeris Blog 