Archive
01/12/2018 – Ephemeris – A look at Gemini the very unusual twins
Ephemeris for Friday, January 12th. The Sun will rise at 8:18. It’ll be up for 9 hours and 6 minutes, setting at 5:24. The Moon, half way from last quarter to new, will rise at 5:16 tomorrow morning.
The constellation Gemini, the Twins is visible half way up the sky in the east at 9 p.m. The namesake stars of the two lads will be on the upper left edge of the constellation, nearly vertically aligned. Castor is above, while Pollux, a slightly brighter star is below it. Lines of stars from Castor and Pollux to the right delineate the lads. In Greek mythology Castor and Pollux were twins, and half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus in the famous Leda and the swan affair. The brothers, however were inseparable, and when Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also. Zeus granted his wish, so they both appear in the sky together forever.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Gemini as it should appear at 9 p.m., January 12, 2018. Created using Stellarium.
Gemini with Castor and Pollux. A closeup with a different way to link the stars with constellation art. Created with Stellarium.
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.
02/16/2017 – Ephemeris – The Winter Circle
Ephemeris for Thursday, February 16th. The Sun will rise at 7:40. It’ll be up for 10 hours and 32 minutes, setting at 6:12. The Moon, 2 days before last quarter, will rise at 12:17 tomorrow morning.
The winter skies are blessed with more first magnitude stars than any other season. These are the twenty-one brightest stars in the sky. Six of these stars lie in a large circle centered on the seventh. This circle is up all evening now that we are in the heart of winter. Starting high overhead is Capella in Auriga the charioteer. Moving clockwise, we come to Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee we find Rigel. Down and left is the brightest star of all Sirius the Dog Star in Canis Major Orion’s large hunting dog, lowest of these stars in the south. Moving up and left there is Procyon in Canis Minor, Then above it is Pollux in Gemini the twins. All are centered on Betelgeuse in Orion.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Winter Circle of 1st magnitude stars. Created using my LookingUp program.
01/27/2017 – Ephemeris – The celestial twins
Ephemeris for Friday, January 27th. The Sun will rise at 8:06. It’ll be up for 9 hours and 38 minutes, setting at 5:44. The Moon is new today, and won’t be visible.
The constellation Gemini, the Twins is visible high in the southeast at 9 p.m. The namesake stars of the two lads, will be high on the upper left edge of the constellation, nearly vertically aligned. Castor is above, while Pollux, a slightly brighter star is below it. Lines of stars from Castor and Pollux to the lower right delineate the lads. In Greek mythology Castor and Pollux were twins, and half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus in the famous Leda and the swan affair. The brothers, however were inseparable, and when Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also. Zeus granted his wish, so both appear in the sky together forever.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Gemini revealed by animation. Created using Stellarium and GIMP.
02/18/2016 – Ephemeris – Castor and Pollux
Ephemeris for Thursday, February 18th. The Sun will rise at 7:39. It’ll be up for 10 hours and 35 minutes, setting at 6:14. The Moon, 3 days past first quarter, will set at 5:28 tomorrow morning.
The star Pollux is at the head of the same named brother of Gemini the twins. Castor is the slightly dimmer star right above it. Pollux is about 34 light years away. It’s twice as massive as the Sun, and has run out of hydrogen in its core and is in the process of evolving into a red giant star. One planet, twice as massive as Jupiter has been detected around it. Castor is at 51 light years away. There are 6 stars in its system. The brightest three are visible in telescopes. Each is a spectroscopic binary, meaning that the companion stars are detected by the Doppler shifts of the lines in their spectra as the stars orbit each other. The Doppler shift is just one of the many pieces of information revealed by the spectroscope.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Castro and Pollux with the bright Moon and other bright stars and constellations of winter. 9 p.m. February 18, 2016. Created using Stellarium.
The Castor star system exploded in this JPL/NASA infographic.
The entire infographic is here.
02/12/2016 – Ephemeris – A circle of bright stars in winter
Ephemeris for Friday, February 12th. The Sun will rise at 7:48. It’ll be up for 10 hours and 18 minutes, setting at 6:06. The Moon, 3 days before first quarter, will set at 11:19 this evening.
The winter skies are blessed with more first magnitude stars than any other season. With the moon out these stars will stand out even more, as dimmer stars are suppressed. Six of these stars lie in a large circle centered on the seventh, the Winter Circle.
This circle is up at 9 p.m. Starting high nearly overhead is Capella in Auriga the charioteer. Moving clockwise down to the south, we come to Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee we find Rigel. Down and left is the brightest star of all Sirius in Canis Major Orion’s large hunting dog, lowest of these stars in the southeast. Moving up and left there is Procyon in Canis Minor, Above is Pollux in Gemini the twins. All are centered on Betelgeuse the bright red star in Orion’s shoulder.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The bright stars of winter arrayed in a circle. Created using Stellarium.
Some also see a Winter Triangle consisting of the stars Betelgeuse, Sirius and Procyon.
01/11/2016 – Ephemeris – Gemini, the half-brothers that are twins
Ephemeris for Monday, January 11th. The Sun will rise at 8:18. It’ll be up for 9 hours and 4 minutes, setting at 5:22. The Moon, 2 days past new, will set at 7:36 this evening.
Before the Moon brightens the evening sky, lets look at another of the winter constellations. The constellation Gemini, the Twins is visible high in the east-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, vertically aligned. Castor is on top, while Pollux is below. From them come 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, but were born together. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so both appear together in the sky forever.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Gemini revealed by animation. Created using Stellarium and GIMP.
02/16/2015 – Ephemeris – The Winter Circle
Feb 16. This is Bob Moler with Ephemeris for President’s Day, Monday, February 16th. The sun will rise at 7:42. It’ll be up for 10 hours and 30 minutes, setting at 6:12. The moon, 2 days before new, will rise at 6:25 tomorrow morning.
The winter skies are blessed with more first magnitude stars than any other season. That’s a full one-third of the total are seen is a relatively small area. Six of these stars lie in a large circle centered on the seventh. This circle is up at 9 p.m. Starting high overhead is Capella in Auriga the charioteer. Moving down clockwise is Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee we find Rigel. Down and left is the brightest star of all Sirius the Dog Star in Canis Major, lowest of these stars in the south-southeast. Moving up and left is Procyon in Canis Minor, Above Procyon is Pollux in Gemini the twins. All these are centered on Betelgeuse the bright red star in Orion’s shoulder.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Winter Circle of 1st magnitude stars
02/13/2015 – Ephemeris – The stars Castor and Pollux
Ephemeris for Friday, February 13th. The sun will rise at 7:46. It’ll be up for 10 hours and 21 minutes, setting at 6:08. The moon, 2 days past last quarter, will rise at 3:51 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, one 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.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Gemini with the stars Castor and Pollux. Created using Stellarium.
11/20/2014 – Ephemeris – Constellation rotation from rise to set
Ephemeris for Thursday, November 20th. The sun will rise at 7:45. It’ll be up for 9 hours and 24 minutes, setting at 5:10. The moon, 2 days before new, will rise at 6:38 tomorrow morning.
At 9 p.m., if it’s clear tonight look to the east to see the bright winter constellation Orion the hunter mostly risen over the eastern horizon as Robert Frost told in his poem Star-Splitter. Orion’s throwing a leg up over the horizon, climbing into the sky. The three stars of Orion’s belt are nearly vertical as the mighty hunter rises. When in the spring he sets those stars will be horizontal. The same is true on the two namesake stars of the twins of Gemini Castor and Pollux to Orion’s left rising in then east-northeast. They rise vertically aligned and set horizontally. It’s due to our latitude and the fact that these stars are near the equator of the sky. At the poles the stars don’t change attitude, and don’t rise or set. Here they flip about 90 degrees, and at the equator they do a 180. Interesting.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Orion rising at 9 p.m. on November 20, 2014. Note that Orion’s Belt stars and Gemini’s namesake stars are nearly vertically aligned. Created using Stellarium.
Orion setting near the end of twilight in April 2015. Note that Orion’s Belt stars and Gemini’s namesake stars are now nearly horizontally aligned. Created using Stellarium.
Bob Moler's Ephemeris Blog 