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Ephemeris: 08/29/2024 – Centaur or Teapot, you decide!
This is Bob Moler with Ephemeris for Thursday, August 29th. Today the Sun will be up for 13 hours and 21 minutes, setting at 8:23, and it will rise tomorrow at 7:03. The Moon, 3 days past last quarter, will rise at 3:02 tomorrow morning.
Low in the south at 10 PM shines the heart of summer Milky Way. The constellation that’s seen there is Sagittarius which is supposed to be a centaur with a bow and arrow. We modern folk haven’t seen a centaur outside a Harry Potter movie, so we see its stars looking like a teapot, a short and stout little teapot like in the children’s song. It is tipped to the West with the Milky Way like steam rising from its spout, which is about to pour its tea on the southwestern horizon later tonight. Sagittarius is just begging to be explored with binoculars or a very low power telescope to see its myriad of stars, star clusters and nebulae. As fabulous as all this appears, we cannot see into the heart of the Milky Way for all the clouds of dust and gas in the way.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). Times will be different for other locations.
Addendum
My first guide to the constellations was Stars by Zim and Baker, a Golden Guide. I checked, it has been revised and is still available. H. A. Rey’s book is also still available.
Ephemeris: 08/05/2024 – Finding Aquila the Eagle
This is Ephemeris for Monday, August 5th. Today the Sun will be up for 14 hours and 28 minutes, setting at 9:02, and it will rise tomorrow at 6:35. The Moon, 1 day past new, will set at 9:58 this evening.
The bright star Altair is seen halfway up the sky in the southeast at 10:30 this evening. It is one of the stars of the Summer Triangle with Vega above it, and Deneb above and left of it. It is the brightest star in the constellation Aquila the eagle which is seen flying northward through the Milky Way, with Altair at its head. Altair is flanked by two stars one above one below. Its wing tips can be seen below, and to the upper right. His tail is almost lost in the Milky Way seen lower in the east southeast. Here in Aquila is where the great rift, the dark band that splits the Milky Way, is most prominent. The Greeks and Romans seemed to have trouble telling vultures and eagles apart. Another name of the constellation was Vultur Volans.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They will be different for other locations.
Addendum
Ephemeris: 08/02/2024 – The Northern Cross
This is Ephemeris for Friday, August 2nd. Today the Sun will be up for 14 hours and 35 minutes, setting at 9:06, and it will rise tomorrow at 6:31. The Moon, 2 days before new, will rise at 5:12 tomorrow morning.
The star Deneb is high in the east-northeast. It is the dimmest of the three stars of the Summer Triangle. It is at the head of the Northern Cross, an informal constellation or asterism. The upright extends to the South. The crossbeam can be seen crossing the star just south of Deneb. There’s also a constellation there. It’s actually Cygnus the swan flying southward along the Milky Way with its neck outstretched. The Anishinaabe natives peoples of our area see Ajijaak the crane, also with a long neck flying north, but also long legs trailing to the south, its wings outstretched. In Greek mythology Cygnus was the guise of the god Zeus when he seduced Leda, whose offspring was Pollux, one of the Gemini twins.
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
Ephemeris: 07/30/2024 – The heavenly harp
This is Ephemeris for Tuesday, July 30th. Today the Sun will be up for 14 hours and 42 minutes, setting at 9:10, and it will rise tomorrow at 6:28. The Moon, 3 days past last quarter, will rise at 2:08 tomorrow morning.
After it gets dark, nearly overhead, appears the bright star Vega, the brightest of the stars of the Summer Triangle. It is part of the constellation called Lyra the harp. The form of the harp is a lyre, which has a U-shaped frame with a bar across the top, the strings are strung from the bar down to the base of the U. According to Greek myth it was invented by the god Hermes who used a tortoise shell as the base of the U. He gave it to Apollo, who in turn gave it to Orpheus. Orpheus had the greatest musical talent. His singing and lyre playing would make animals and even inanimate objects dance. The constellation itself consists of Vega and a parallelogram of four stars which are seen below it.
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
Ephemeris: 07/25/2024 – The Milky Way as it will appear tonight
This is Ephemeris for Thursday, July 25th. Today the Sun will be up for 14 hours and 54 minutes, setting at 9:16, and it will rise tomorrow at 6:23. The Moon, 2 days before last quarter, will rise at 11:43 this evening.
With the Moon out of the sky until almost 11:30 PM we get our first look at the summer Milky Way in the evening. The Milky Way will stretch from the east-northeast, high in the east to the South. The asterism of the stout little Teapot in Sagittarius, low to the south, is near the bottom end of the Milky Way. The milky stream appears as steam coming out of the spout. With more stars there, one might be able to see the Centaur with a bow and arrow. The front part of the teapot is the bow. The bottom left, and the far right star are the back and the tip of the arrow which is pointing at the heart of Scorpius the scorpion in the south-southwest. We’ll be exploring the wonders of the summer Milky Way this month and next.
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
Ephemeris Extra: 07/02/2024 – A closer look at Corona Borealis
Adapted from an article that ran in the Stellar Sentinel, the July 2024 newsletter of the Grand Traverse Astronomical Society.
A small constellation is getting a lot of attention this year because we expect a bright nova to appear in it sometime in the next few months. The constellation is Corona Borealis, the Northern Crown. It is a small constellation between the Boötes and the bright star Arcturus and Hercules, and farther off to the east the bright star Vega. Corona Borealis contains seven stars in the 2/3 circle of stars. Its brightest star is the third star from the right. It’s the second magnitude star called Alphecca. In Arabic, it means The Bright Star of the Broken Ring of Stars, which is a pretty good description of it. It is also known as Gemma though it sounds like a gem in a crown, it actually means blossom which would appear in a floral crown.
In Greek mythology the crown was given to the Princess Ariadne. The story goes like this. During the time of the Minoan civilization on Crete, It was ruled by King Minos, whose daughter was Ariadne. The Minoans apparently had defeated Athens in battle and had extracted tribute from them. That yearly tribute being the sacrifice of the young man or maiden to enter the Labyrinth which was home to a monster called the Minotaur. In this story a fellow by the name of Theseus from Athens was sent to Crete to face the Minotaur. He fell in love with Ariadne, but he had to enter the Labyrinth, so she provided him with a spool of thread so he could find his way back out again after he had slain the Minotaur, if he was able to. He entered the Labyrinth and found the Minotaur. Theseus was able to slay the beast, and was able to follow the thread back out. Theseus and Ariadne fled to the Island of Naxos where he married her. However, he soon abandoned her. As consolation, the god Dionysus gave her a crown. She kept the crown until she remarried, and it was placed in the sky where we see it today.
For the Anishinaabe native peoples of our area Corona Borealis becomes the Sweat Lodge. Other indigenous peoples of North America see these stars as circles of maidens, or other circles. To the Aborigines of Australia who see Corona Borealis very low in the north, it’s Woomera, the boomerang.
The constellation has two famous variable stars. The one we’re expecting to flare up this year, up to second magnitude as a nova, is T Coronae Borealis (T CrB), sometimes called the Blaze Star. It was recorded in 1866 and at even earlier times, and was naked eye for eight days, dropping a half magnitude per day. It also blazed forth in 1946, making it one of the few known recurrent novas. In 1946 the star, normally 10th magnitude, barely visible in binoculars, underwent a slight dimming about 11 months before it blazed forth as a nova. This has already happened last year, so we are expecting it soon to blaze forth again. It will appear to the lower left, just outside the circle of stars in the crown, and will grow as bright as Alphecca.
Novas, also in the case of T CrB, are close binary stars containing a large star and a white dwarf. A white dwarf is a star at the end of its life, and has run out of hydrogen or other light elements in its core to keep it sustained. So it shrinks down to about the size of the Earth, even though it has the mass of the Sun or a little more. It orbits with the larger star and is basically siphoning off gas from that large star onto its surface, enough gases accumulate on the star for a thermonuclear reaction to occur, and it becomes a nova, brightening thousands of times for a few days. The white dwarf survives to do it all over again in some cases.
Corona Borealis’ other famous variable star is R Coronae Borealis, a star that’s normally about 6th magnitude that irregularly dips down to 10th or even dimmer. The mechanism for this appears to be that the star is surrounded by clouds of dust that periodically block it from our view.
If you’re interested in observing variable stars, check out the American Association of Variable Star Observers: https://www.aavso.org/
If there’s a Northern Crown, there should be a Southern Crown, and there is. It is Corona Australis made of dim stars, and it is located just below the constellation of Sagittarius, right below the Teapot asterism, which is very low on our southern horizon after midnight this month, but better seen in August.
Ephemeris: 7/02/2024 – Antares and the scorpion
This is Bob Moler with Ephemeris for Tuesday, July 2nd. Today the Sun will be up for 15 hours and 29 minutes, setting at 9:31, and it will rise tomorrow at 6:02. The Moon, 3 days before new, will rise at 3:26 tomorrow morning.
The constellation of Scorpius the scorpion is low in the south at 11 PM these nights. It’s bright star Antares will pass due south at 11:30 this evening. Antares is an interesting star in that it is a red giant star, and its name Antares* means “Rival of Mars” alluding to the fact that it and Mars appears to be the same color. And about every two years Mars passes near Antares, so unless you know your stars and planets you could mistake them for each other. Antares lies at the heart of the scorpion. To its upper right is the front part of its body and claws, and the trail of stars running down the other way, nearly to the horizon, in the south and back up in the south-southeast to the two stars of its stinger make its characteristic tail.
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.
*Breaking down Antares: Ant (Anti, against) – Ares (The Greek god of war the Romans called Mars).
Addendum
Note for trivia fans: Zubeneschamali is the longest star name at 14 letters.
Ephemeris: 06/10/2024 – Finding Draco the Dragon
This is Ephemeris for Monday, June 10th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, halfway from new to first quarter, will set at 1:09 tomorrow morning.
High in the northern sky at 11 p.m. lies the twisted constellation, that of Draco the dragon. This dragon is more like the snakelike Chinese dragon than the dinosaur-like dragon of European legend. I find it better to start at the tail of Draco, to trace him out in the stars. Draco’s tail starts, or ends, between the bowl of the Big Dipper and the Little Dipper high in the north-northwest. The Dragon is seen in a line of stars that extends parallel to the handle of the Big Dipper before curving around the bowl of the Little Dipper then bends back down to the level of Polaris in the north-northeast before turning toward the east. The head of Draco is an odd box of stars near the bright star Vega, high in the east. Though not made up of very bright stars, Draco has an easy shape to trace.
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
Ephemeris: 06/04/2024 – Finding the Little Dipper
This is Ephemeris for Tuesday, June 4th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:24, and it will rise tomorrow at 5:58. The Moon, 2 days before new, will rise at 4:51 tomorrow morning.
One of the constellations I don’t talk about much, except in passing is Ursa Minor, the Little Bear with an impossibly long tail. It is better known as the Little Dipper. As a dipper goes, its handle is bent the wrong way, like someone stepped on it. Anyway, this time of year in the evening, it’s standing on the tip of it’s handle, which is the North Star, Polaris. Polaris is pointed to by the front two stars of the Big Dipper. As dippers go they pour their contents into each other. The second and third-brightest stars of the Little Dipper are at the front of the bowl, and are Kochab and Pherkad, the Guard Stars, that is, Guardians of the Pole. To the Anishinaabe native peoples of our area the Little Dipper is Maang, the Loon.
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
Ephemeris: 05/30/2024 – Virgo and what’s hidden within
This is Bob Moler with Ephemeris for Thursday, May 30th. Today the Sun will be up for 15 hours and 18 minutes, setting at 9:20, and it will rise tomorrow at 6:00. The Moon, at last quarter today, will rise at 2:52 tomorrow morning.
One of the large constellations we see in the south at 11 p.m. can be found using the Big Dipper overhead, follow the arc of the handle to the bright star Arcturus, then straighten the arc to a spike to reach Spica, a bright blue-white star in the south. Spica is the brightest star in the constellation Virgo, the virgin. She represents the goddess of the harvest, Virgo is holding a sheaf of wheat in depictions of her, and Spica is placed at the head of the sheaf. In the space between Spica and Leo the lion to her upper right is, a great cluster of thousands of galaxies just below naked eye visibility. The Virgo Cluster. Inside that cluster is galaxy M87, in whose center lies a black hole with the mass of 6.5 billion suns. The center of the cluster is at about 54 million light years away. The first black hole imaged by the Earth spanning Event Horizon Telescope.
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
Bob Moler's Ephemeris Blog 