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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.
01/31/2022 – Ephemeris – The winter circle of bright stars
This is Ephemeris for Monday, January 31st. Today the Sun will be up for 9 hours and 47 minutes, setting at 5:50, and it will rise tomorrow at 8:01. The Moon, 1 day before new, will rise at 8:48 tomorrow morning.
The winter skies are blessed with more first magnitude stars than any other season. Six of these stars lie in a large circle centered on the seventh, It’s called the Winter Circle. This circle is up in the evening. Starting high overhead is yellow Capella in Auriga the charioteer. Moving down clockwise is orange Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee, we find blue-white Rigel. Down and left is the brightest star of all the brilliant white Sirius the Dog Star in Canis Major, lowest of these stars in the south-southeast. Moving up and left is white Procyon in Canis Minor, Above Procyon is Pollux in Gemini, the twins. All these are not quite centered on Betelgeuse, the bright red star in Orion’s shoulder.
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
The bright stars of winter arrayed in a not so accurate circle. Some call it the Winter Hexagon. These stars are what make the winter sky so brilliant on the rare clear night in winter. Created using Stellarium.
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.
04/13/2021 – Ephemeris – Hydra slithers across the southern sky
This is Bob Moler with Ephemeris for Tuesday, April 13th. Today the Sun will be up for 13 hours and 24 minutes, setting at 8:25, and it will rise tomorrow at 6:59. The Moon, 2 days past new, will set at 10:08 this evening.
In the southern evening sky can be found the constellation of Hydra the water snake. Unlike the monster of the same name this Hydra has but one head, which is its most distinctive part. At 10 p.m. look midway up the sky in the south-southwest. The head of Hydra is located below a line from the constellation Leo the Lion in the south and Gemini high in the west-southwest. Its head is directly below Cancer the crab in the southwest. Hydra’s head is a small but distinctive group of 6 stars that make a loop and the snake’s slightly drooping head. The rest of Hydra wends its way to the southeastern horizon, and eventually ends near the late spring constellation of Libra the scales. Over the next few hours Hydra will be seen slithering across the southern sky.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
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.
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.
03/10/2020 – Ephemeris – A Closeup look at Gemini’s namesake stars
Ephemeris for Tuesday, March 10th. Today the Sun will be up for 11 hours and 39 minutes, setting at 7:43, and it will rise tomorrow at 8:01. The Moon, 1 day past full, will rise at 9:07 this evening.
At 9 p.m. the constellation of Gemini the twins will be seen high in the south-southeast. The namesake stars of the two lads are the two bright stars at the upper left 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 two stars can be detected by the rainbow colors of light from the star. 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 it at a distance somewhat greater than Mars is from the Sun. Pollux is 34 light years away while Castor is 50 light years away.
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 at 9 p.m. March 10th, 2020. Created using Stellarium.
Castor and Pollux namesakes of the twins of Gemini in its position at 9 p.m. EDT March 10th. Created using Stellarium.
The Castor star system exploded in this JPL/NASA infographic.
05/09/2019 – Ephemeris – The USA: Step by step to the Moon
Ephemeris for Thursday, May 9th. Today the Sun will be up for 14 hours and 35 minutes, setting at 8:57, and it will rise tomorrow at 6:20. The Moon, 2 days before first quarter, will set at 1:54 tomorrow morning.
The Apollo 11 manned landing on the Moon 50 years ago was the culmination of a series of incremental steps. The Mercury program was in progress when President Kennedy announce the goal to land on the Moon. Following that was Gemini a two man capsule to test long duration flight, rendezvous and docking of two spacecraft, and EVA’s or spacewalks. There was the Ranger program attempted to photograph the Moon close up by sending probes to crash into the Moon. The Lunar Orbiter program to map the entire Moon, the Surveyor program to soft land on the Moon and test its surface. All this leading up to the three man Apollo program to test out the strategy and equipment and to land humans on the Moon.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Project Mercury astronauts and a model of the Mercury-Atlas rocket and capsule. Left to right: Grissom, Shepard, Carpenter, Schirra, Slayton, Glenn and Cooper, in 1962. Click on the image to enlarge. Credit NASA.
Project Gemini: Left Ed White during the US first space walk during Gemini 4 in June of 1965. Right The rendezvous of Gemini 6 & 7 in December of 1965. Click on the image to enlarge. Credit NASA.
Left: The Ranger spacecraft. Right: The floor of the crater Alphonsus from Ranger 9. Only the last 3 spacecraft were successful. They transmitted images all the way down as they crashed into the Moon. Click on the image to enlarge. Credit NASA.
In the most unheralded of the lunar programs the 5 successful Lunar Orbiter satellites photographed 99% of the Moon. from 1966 to 1967. The Moon was photographed on film in strips, developed and the images scanned and transmitted back to Earth. Right: The oblique view of the crater Copernicus was dubbed at the time “The Picture of the Century”. Click on the image to enlarge. Credit NASA.
Surveyor 3, visited by astronaut Pete Conrad during the Apollo 12 mission. Click on the image to enlarge. Credit: NASA / Alan Bean.
Bob Moler's Ephemeris Blog 