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09/27/2022 – Ephemeris – Finding the constellation of Perseus the hero

September 27, 2022 Comments off

This is Ephemeris for Tuesday, September 27th. Today the Sun will be up for 11 hours and 54 minutes, setting at 7:30, and it will rise tomorrow at 7:37. The Moon, 2 days past new, will set at 8:28 this evening.

Close to the horizon, but rising in the northeast in the evening, is the constellation of Perseus the Greek hero, holding as his prize the severed head of Medusa. To me, the stars don’t seem to match the figure in the stars. It’s either the Greek letter pi (π) tilted to the left or the cartoon roadrunner running up the sky. Perseus’ brightest star is Mirfak in the middle of the top of the letter π, or back of the roadrunner. Using a pair of binoculars to look towards Mirfak, one can see many more stars, just below naked eye visibility near it. It’s a very loose star cluster called the Alpha (α) Persei Association, α Persei being a catalog designation for Mirfak. And Mirfak is actually in the association. Unlike some bright stars, who are just foreground stars.

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

For my take on the mythology featuring Perseus, see The Great Star Story of Autumn. It’s way too long for my short radio program. For Hollywood’s treatment of the story, see Clash of the Titans.

Perseus finder animation

Perseus finder using the animated GIF to show the star field, constellation lines and names, and Perseus as art. Cassiopeia is included as a means to find the dimmer Perseus below it on autumn evenings. Algol, another important star and the second-brightest star of Perseus, is also labeled. I normally cover it around Halloween, but if you can’t wait, type Algol in the search box at the upper right. Created using Stellarium, LibreOffice Draw, and GIMP.

Alpha Persei Association

The Alpha Persei Association. The brightest star is Mirfak (Alpha Persei). This is a small section of a photograph taken February 18, 2017, Canon EOS Rebel T5, 121 seconds, f/3.5, 18 mm fl., ISO 3200. Credit Bob Moler.

09/20/2022 – Ephemeris – Finding the constellation of Pegasus the flying horse

September 20, 2022 Comments off

This is Ephemeris for Tuesday, September 20th. Today the Sun will be up for 12 hours and 16 minutes, setting at 7:43, and it will rise tomorrow at 7:28. The Moon, 3 days past last quarter, will rise at 2:33 tomorrow morning.

Rising about a third of the way up the sky in the east as it gets dark around 9 pm can be found one of the great autumn constellations: Pegasus the flying horse of Greek myth. Its most visible feature is a large square of four stars, now standing on one corner. This feature, called the Great Square of Pegasus, represents the front part of the horse’s body. The horse is quite aerobatic, because it is seen flying upside down. Remembering that fact, the neck and head is a bent line of stars emanating from the right corner star of the square. Its front legs can be seen in a gallop extending to the upper right from the top star of the square. From the left star extend, not hind legs but the constellation of Andromeda, the princess rescued with the help of Pegasus.

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

Pegasus-Andromeda finder

Pegasus & Andromeda animated finder chart for 9 pm in mid-September. To the upper left are most of the stars of the “W” shape of Cassiopeia the queen, Andromeda’s mother. Created using Stellarium and GIMP.

Pegasus, Andromeda and Cassiopeia plus other constellations are characters in the great star story of autumn which I relate here.

09/19/2022 – Ephemeris – Finding the constellation Cepheus

September 19, 2022 Comments off

This is Ephemeris for Monday, September 19th. Today the Sun will be up for 12 hours and 19 minutes, setting at 7:45, and it will rise tomorrow at 7:27. The Moon, 2 days past last quarter, will rise at 1:30 tomorrow morning.

There’s a faint constellation in the northeast above the W shaped constellation of Cassiopeia. It’s a nearly upside down church steeple of a constellation called Cepheus the king, and husband of queen Cassiopeia. Cepheus’ claim to modern astronomical fame is that one of its stars, Delta (δ) Cephei, is the archetype for the important Cepheid variable stars. Delta is the bottom most of a trio of stars at the right corner of the constellation. In the early 20th century, Henrietta Leavitt discovered that Cepheids in the nearby galaxy the Large Magellanic Cloud varied in brightness with a period that was related to their average brightness. This meant that Cepheids could be used as standard candles to measure the great distances to other galaxies.

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

Cassiopeia and Cepheus finder animation

Cassiopeia and Cepheus finder animation looking in the northeast at 9 pm or about an hour after sunset in mid-September. Also labeled is Delta (δ) Cephei. Created using Stellarium and GIMP.

Delta_Cephei_lightcurve

Light Curve of Delta Cephei. The pulsation period is 5.367 days. Note the Magnitude vertical axis, the lower the magnitude the brighter the star is. Blame that on the Greek astronomer Hipparchus, 2nd century BC. It’s like golf scores; the lower the score, the better the golfer, and for magnitudes, the brighter the star. Credit: Thomas K Vbg – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=13887639.

Ephemeris Extra – Wandering through Sagittarius

August 8, 2022 Comments off

Annotated Sagittarius photograph

Sagittarius in a short time exposure with added annotations. The “M” designations are objects in Charles Messier’s catalog created in the latter half of the 18th century. LSSC is the Large Sagittarius Star Cloud, SSSC is the Small Sagittarius Star Cloud. Credit Bob Moler.

Sagittarius is seen low in the south in August. It’s between Scorpius to the west, and Capricornus, rising in the southeast. The name Sagittarius simply means archer. It doesn’t describe the fact that the archer isn’t just any old bloke with a bow and arrow, but is, indeed, a centaur, one of the two in the list of constellations. The other, Centaurus, is too far south to be seen from Michigan. And whose brightest star, Alpha Centauri, is in the closest star system to our solar system.
Centaurs, as a rule, were a rowdy bunch, the ancient Greek equivalent to a modern motorcycle gang. However, the centaur depicted by Sagittarius can be thought to be Chiron, though it can also be ascribed to Centaurus. Chiron was learned, a teacher and physician. I’ve noticed that in some artist’s depictions of Chiron, he is teaching Achilles how to use the bow and arrow. He also taught medicine to Asclepius, the great physician, who is seen in the heavens as the constellation Ophiuchus, above and right of Sagittarius.
What most of us see in the stars here is maybe a bow drawn to shoot at the heart of Scorpius, or a stout little teapot as in the children’s song. It even has the Milky Way seeming to rise from the spout like steam. The teapot rises in the southeast as if standing upright, and as the night wears on, it rises and move westward, slowly tilting to pour out its tea on the southwestern horizon.
The area of Sagittarius and the Milky Way is a fantastic part of the sky to explore with binoculars or a low power telescope on moonless nights. At the head of this post is a photograph of Sagittarius and the Milky Way taken from my home, with lines and labels. It’s somewhat spoiled by the sky glow from Chum’s Corner, a small commercial center 3.6 miles away, from the lower left. Most binoculars will show open or galactic star clusters as fuzzy spots like nebulae, which are fuzzy because they are clouds. The older globular star clusters require larger amateur telescopes to resolve.
I’ve only pointed out one in the image, that’s M22, whose designation, we have fun with at star parties at the Sleeping Bear Dunes National Lakeshore, since the road M22 runs through the park. Which came first? That’s easy, Charles Messier cataloged his 22nd object before Michigan was a state or even had roads. Well, maybe there were a few, around Detroit and Sault Ste. Marie, back when the major “roads” were the Great Lakes, and the rest Indian trails.
A telescope, even a small one, will resolve open clusters, showing individual stars. Telescopes will show the shapes of nebulae if they are bright enough.
One nebula with a distinctive shape is M17. The descriptive name I first knew it as was the Omega Nebula, and also the Horseshoe Nebula. To me, it never looked like either. It looked like a check mark, or a somewhat short necked swan. And it also goes by those names too. The planetarium program I use a lot, Stellarium, also calls it the Lobster nebula. I’m not much for seafood, but it doesn’t look like a lobster, or maybe I’m not hungry enough.
M16, is the Eagle Nebula. It has an associated star cluster. My eyes are drawn to the star cluster. The nebulosity is very faint, and I usually can’t see it. Part of the nebula was famously photographed by the Hubble Space Telescope and called the Pillars of Creation. In actuality, they are the Pillars of Destruction as they are being blown away by the stellar winds of the star cluster.
M8 is the Lagoon Nebula, it also has an associated star cluster. In telescopes, it is crossed by a narrow dust cloud suggestive of a lagoon. Nearby M20 is the Trifid nebula, which has a low surface brightness and can easily be missed. It is crossed by three narrow dust clouds dividing it into three, or on closer inspection, four wedges.
These just scratch the surface. So with or without optical aid wander through the celestial wonders and star clouds of Sagittarius. You have August and September to do it in the evening before they set for another year.

Based on an article I wrote for the August 2022 issue of the Stellar Sentinel, the Newsletter of the Grand Traverse Astronomical Society.

07/19/2022 – Ephemeris – How to find the constellations of the man with the snake

July 19, 2022 Comments off

This is Ephemeris for Tuesday, July 19th. Today the Sun will be up for 15 hours and 7 minutes, setting at 9:22, and it will rise tomorrow at 6:16. The Moon, 1 day before last quarter, will rise at 12:52 tomorrow morning.

The red star Antares shines in the south at 11 pm, in the constellation of Scorpius. In the area of sky above lies a large constellation of faint stars called Ophiuchus, the serpent bearer. The constellation shape is like a large tilted bell, which reminds me of the head, shoulders and arms of a fellow that’s holding the snake, like a weight lifter pulling up a heavy barbell. The serpent he’s holding is Serpens, the only two-part constellation in the heavens. The head rises to Ophiuchus’ right, and the tail extends up to the left. In Greek legend Ophiuchus represents a great physician, educated by the god Apollo, and the centaur Chiron, who is also found in the stars as Sagittarius, now rising in the south-southeast below and left of him.

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

Ophiuchus finder animation

Ophiuchus finder animation for mid-July at 11 pm. Created using Stellarium and GIMP.

06/28/2022 – Ephemeris – Finding the celestial harp

June 28, 2022 Comments off

This is Ephemeris for Tuesday, June 28th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:32, and it will rise tomorrow at 6:00. The Moon is new today, and won’t be visible.

High in the east at 11 p.m. can be found a bright star just above a small, narrow, but very distinctive parallelogram of stars. They are the stars of the constellation Lyra the harp. The bright star is Vega, the 4th or 5th brightest nighttime star*, and currently the topmost star of the Summer Triangle. To the Romans, the star Vega represented a falling eagle or vulture. Apparently they never made the distinction between the two species. It is a pure white star and serves as a calibration star for color and brightness. In the evening, it is the top-most star of the Summer Triangle. The harp, according to Greek mythology, was invented by the god Hermes. The form of the harp, in the sky, is as he had invented it: by stretching strings across a tortoise shell. Hermes gave it to his half-brother Apollo, who in turn gave it to the legendary musician Orpheus.

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.

*Vega’s rival for the fourth spot on the brightness list is Arcturus to it’s west. Wikipedia’s source says that Arcturus is slightly brighter. Stellarium’s source says Vega is brighter. The difference is a few hundredths of a magnitude. However, they are of different colors. Vega is pure white, while Arcturus is yellow-orange because it has a cooler surface temperature than Vega. Check them out for yourself.

Addendum

Annimated Lyra finder chart

Animated Lyra finder chart. The lyre image not supplied by Stellarium but is from The World’s Earliest Music by Hermann Smith, Figure 60, A Project Gutenberg E-Book, and captioned “The Chelys or Greek Tortoiseshell Lyre”. The three names stars are the stars of the Summer Triangle in the eastern sky these evenings of late June. Created using Stellarium.

06/24/2022 – Ephemeris – Finding the greatest celestial hero: Hercules

June 24, 2022 Comments off

This is Ephemeris for Friday, June 24th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, halfway from last quarter to new, will rise at 3:31 tomorrow morning.

Orion, the hard luck mythical Greek hunter, gets a splashy constellation in the winter sky, but the greatest hero of all, Hercules, gets a dim group of stars on the border between the spring and summer stars. At 11 p.m. Hercules is high in the southeast. It is located right of the bright star Vega, in the east. Hercules’ central feature is a keystone shaped box of stars, called, of course, the Keystone of Hercules tilted to the left, which represents the old boy’s shorts. From the top and left corner stars extend lines of stars that are his legs, from the bottom and right stars, the rest of his torso and arms extend. So in one final indignity, he’s upside down in our sky. For those with a telescope, Hercules contains the beautiful globular star cluster Messier 13.

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

Hercules finder

Hercules animation showing neighboring stars at 11 p.m. for mid-June. Click on image to enlarge. Created using Stellarium.

Hercules globular star cluster finder

Hercules with all the stars visible in binoculars and its two globular star clusters: M13 and M92. M13 is almost bright enough to be spotted with the naked eye. It is easily visible in binoculars as a tiny fuzzy spot. It takes a telescope with an aperture of 6 – 8″ or 150 – 200 mm to begin to see some individual stars. M92 is dimmer and harder to resolve. Created using Cartes du Ciel (Sky Charts).

M 13

M 13, the Great Globular Star Cluster in Hercules. Credit: Scott Anttila.

06/23/2022 – Ephemeris – Corona Borealis, the Northern Crown

June 23, 2022 Comments off

This is Ephemeris for Thursday, June 23rd. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 3 days past last quarter, will rise at 3:08 tomorrow morning.

High in the south at 11 this evening can be seen a small nearly circular constellation of Corona Borealis, the Northern Crown. It is just left of Boötes, the kite shaped constellation off the handle of the Big Dipper. According to Greek myth, the crown was given by the gods to the princess Ariadne, daughter of King Minos of Crete. The crown is more like a tiara with the bright star Alphecca at the front. To the Anishinaabe people, who are native to our region, it is the Sweat Lodge. Part of what we call Hercules next to it is the Exhausted Bather, who is lying on the ground after the ceremony. The seven stones that are heated for the Sweat Lodge ceremony are the Pleiades, now close to Venus in the morning twilight.

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

Corona Borealis and Sweat Lodge finder animation

Corona Borealis and Sweat Lodge finder animation. Looking high in the south at 11 pm, June 23rd. The tail of Ursa Major or the handle of the Big Dipper is in the upper right. Created using Stellarium and GIMP. Both star lore images are embedded in Stellarium. The Anishinaabe images are embedded in Stellarium and is from Ojibwe Giizhig Anung Masinaaigan – Ojibiwe Sky Star Map created by A. Lee, W. Wilson, and C. Gawboy.

05/19/2022 – Ephemeris – Spring constellations: Virgo

May 19, 2022 Comments off

This is Ephemeris for Thursday, May 19th. Today the Sun will be up for 14 hours and 58 minutes, setting at 9:08, and it will rise tomorrow at 6:09. The Moon, halfway from full to last quarter, will rise at 1:40 tomorrow morning.

Tonight at 11 p.m. in the south is the constellation and member of the zodiac: Virgo the virgin. Virgo is a large constellation of a reclining woman holding a stalk of wheat. Spica, the bluest of the first magnitude stars, is the head of that spike of wheat; and as such it ruled over the harvest in two of Virgo’s guises as the goddesses Persephone and Ceres. Virgo is also identified as Astraea the goddess of justice. The constellation of Libra, the scales, which she is associated with, is found just east of her low in the southeast. Early Christians who sought to de-paganize the heavens saw Virgo as the Virgin Mary. Virgo is the host to a great cluster of galaxies seen far beyond its stars, which belong to our galaxy.

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

Virgo finder animation

Virgo finder animation with Libra added for 11 p.m. tonight, May 19th. Created using Stellarium and GIMP.

Virgo

Virgo as depicted in Urania’s Mirror, a set of constellation cards published in London c.1825. From the Library of Congress. H/T Wikipedia.

Brighter members of the Virgo Cluster. Created using Stellarium.

Brighter members of the Virgo Cluster. Created using Stellarium. Open circles are galaxies, circles with crosses are globular star clusters, outlying members of our Milky Way galaxy.

04/28/2022 – Ephemeris – The story of Arcas and Callisto

April 28, 2022 Comments off

This is Bob Moler with Ephemeris for Thursday, April 28th. Today the Sun will be up for 14 hours and 6 minutes, setting at 8:44, and it will rise tomorrow at 6:35. The Moon, 2 days before new, will rise at 6:16 tomorrow morning.

Appearing in the eastern sky at 10 p.m. tonight is the kite shaped constellation of Boötes the herdsman. The bright star Arcturus is at the bottom of the kite which is horizontal to the left, pointed to by the arc of the handle of the Big Dipper, higher in the east. The Big Dipper is the hind end of the constellation Ursa Major, the Great Bear. In one story, Boötes represents a young hunter named Arcas, son of Callisto, a beautiful young woman who had the misfortune of being loved by god Zeus. Zeus’ wife, Hera, found out about the affair, and since she couldn’t punish Zeus, turned the poor woman into a bear. Arcas, many years later, unaware of why his mother disappeared, was about to kill the bear when Zeus intervened and placed them both in the sky, where he continues to chase her across the sky nightly.

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

Arcas and Callisto

Boötes and Ursa Major aka Arcas chasing Callisto around the pole of the sky. Created using Stellarium.

Arcas and Callisto woodcut

Arcas about to slay the bear by the 17th century artist Baur. Source: University of Virginia Electronic Text Center