Archive
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.
12/15/2015 – Ephemeris – Procyon the star that’s “Before the dog”
Ephemeris for Tuesday, December 15th. The Sun will rise at 8:13. It’ll be up for 8 hours and 49 minutes, setting at 5:02. The Moon, 3 days before first quarter, will set at 9:48 this evening.
Visible low in the east at 9:30 p.m. appears the star Procyon to its lower left is Sirius the brightest night-time star. Procyon is the bright star in the constellation Canis Minor, or lesser dog. I can find only one other star in Canis Minor. Perhaps it’s a hot dog. If Sirius, in Canis major is the Dog Star then Procyon should be the Little Dog Star. However Procyon is an interesting name. It means “Before the dog”, which is an allusion to the fact that Procyon, though east of Sirius actually rises before it. This is due to Procyon’s more northerly position. This effect doesn’t work south of the equator, however. Sirius will rise at about 9 tonight. Procyon is a star much like Sirius but is 32% farther away. It’s 11.4 to Sirius’ 8.6 light years away.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Procyon, Sirius and the stars of winter. Created using Stellarium
In the above chart, beside the constellation lines, we have the grid of right ascension, from lower left to upper right; and declination, from upper left to lower right. right ascension lines are like longitude on the Earth, while declination lines are latitude lines. They are tipped because I don’t live at either the equator or one of the poles. As the Earth rotates the Sun, stars and planets slide westward in the direction of the declination lines. Note that Sirius is closer to the horizon than Procyon. Also that Sirius is west of the 7 hour right ascension line. (Take my word for it.) Procyon is east of that line, thus Sirius is west of Procyon.
Other cool things can be seen in the chart. Note the declination line that touches the horizon at the east compass point and runs just above Orion’s belt. It is 0º declination, or the celestial equator. It extends to the west compass point on the western horizon. The Sun on the equinoxes will rise due east and set due west. The 6 hour right ascension line runs past Betelgeuse in Orion. At 23½º north declination, near Castor’s big toe in Gemini is where the Sun appears on the first day of summer, the summer solstice.
P.S. It was cloudy and rainy the last two days. Didn’t see a Geminid meteor again this year, keeping my record intact.
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.
03/03/2014 – Ephemeris – The dim zodiacal constellation of Cancer the Crab
Ephemeris for Monday, March 3rd. The sun will rise at 7:16. It’ll be up for 11 hours and 16 minutes, setting at 6:33. The moon, 2 days past new, will set at 9:44 this evening.
At 9 this evening, the faint constellation, and member of the Zodiac, Cancer the crab is located in the south-southeast half way between the bright stars Castor and Pollux of the constellation Gemini, high in the south and the bright star Regulus in Leo the lion in the east Cancer is very dim, looking like an upside-down Y. In the center of Cancer is a fuzzy spot to the unaided eye. In binoculars or a low power telescope this fuzzy spot becomes a cluster of stars. It is the Beehive cluster. At 525 light years away, it is one of the closest star clusters, but more distant than the Pleiades and Hyades the face of Taurus the bull. Back a few thousand years ago Cancer was the farthest north of the constellations, Gemini has that honor today.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The constellation Cancer the crab at 9 p.m. March 3, 2014. Created using Cartes du Ciel (Skycharts).
The Beehive star cluster, M44. Its ancient name was the Praesepe or manger when glimpsed by the naked eye. Created using Cartes du Ciel (Skycharts)
02/07/2013 – Ephemeris – The brother stars Castor and Pollux
Ephemeris for Thursday, February 7th. The sun will rise at 7:53. It’ll be up for 10 hours and 6 minutes, setting at 6:00. The moon, 3 days before new, will rise at 6:22 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 belong. 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.
Gemini with Castor and Pollux. Created with Stellarium.
Addendum
02/05/2013 – Ephemeris – The bright stars Castor and Pollux of Gemini
Ephemeris for Tuesday, February 5th. The sun will rise at 7:56. It’ll be up for 10 hours and 1 minute, setting at 5:57. The moon, 2 days past last quarter, will rise at 4:42 tomorrow morning.
The constellation Gemini, the Twins is visible high in the southeast at 9 p.m. The namesake stars of the two lads, will be on the upper left edge of the constellation, diagonally aligned. Castor is to the upper right, while Pollux, a slightly brighter star is below left. 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 and Orion. Created using Cartes du Ciel
06/28/2012 – Ephemeris – Mercury near greatest elongation from the sun
Ephemeris for Thursday, June 28th. Today the sun will be up for 15 hours and 31 minutes, setting at 9:31. The moon, 2 days past first quarter, will set at 2:16 tomorrow morning. Tomorrow the sun will rise at 6:00.
Saturday will be the greatest eastern elongation of Mercury from the sun. It’s a whopping 26 degrees angle east from the sun. Mercury has a markedly elliptical orbit. And when we have a spring eastern elongation, its around 18 degrees from the sun. The best western elongations for us are in the autumn when again the elongation angle is 18 degrees. I won’t go into the why of all this here. But we’re getting an extra good view of this tiny planet. The best time to look for Mercury starts about 10:15 p.m. and ends about 10:45 when Mercury is too close to the horizon. The stars Pollux and Castor of Gemini will appear just to the right of Mercury, and will provide a check that you really have found it.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mercury with the bright stars Pollux and Castor at 10:30 p.m. June 28, 2012. Created using Stellarium.
02/23/2012 – Ephemeris – The star Castor in Gemini
Ephemeris for Thursday, February 23rd. The sun will rise at 7:30. It’ll be up for 10 hours and 50 minutes, setting at 6:21. The moon, 2 days past new, will set at 8:34 this evening.
High in the south southeast at 9 p.m. is the constellation of Gemini the twins. The heads of the two lads contain bright stars with their names. Brighter Pollux is below and Castor is above. Stars that delineate their bodies lie to the lower right of them stretching out in the direction of Orion. Castor is an interesting star because it is actually six stars. Two are easily seen. The two brightest component stars can be resolved in a small telescope. Each has a red dwarf companion detectable only by indirect means. The fifth and sixth stars makes a faint eclipsing binary of red dwarf stars some distance away and very faint. The Castor system resides some 50 light years away.
* 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.
01/23/2012 -Ephemeris – The constellation Gemini the twins
Ephemeris for Monday, January 23rd. The sun will rise at 8:10. It’ll be up for 9 hours and 27 minutes, setting at 5:38. The moon is new today, and won’t be visible.
The constellation of Gemini the twins appears high in the southeast. It appears to the upper left of Orion and the stars that portray his club raised high. Gemini’s two brightest stars are the namesakes of the twins. Castor above and Pollux below. From them there are two lines of stars that form the silhouette of the lads heading to the lower right. In Greek mythology these twins each had a different father, not unheard of in medical history, with Pollux being fathered by the god Zeus and thus immortal. Castor was not. But the brothers were inseparable, so when Castor was killed in the search for the golden fleece Pollux begged his father to let him die too and join his brother. His wish was granted and his devotion was so great that they were placed in the sky where we see them today.
* Times, as always are for the Traverse City/Interlochen area of Michigan.
Addendum
Gemini and Orion. Created using Cartes du Ciel
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