THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
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Altitude: 10 feet below sea level
Founded January 1970
2021-2022: XLIX
“Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less." -Marie Curie
THE DAILY ASTRONOMER
Wednesday, December 1, 2021
December 2021 Night Sky Calendar Part I:
The Winter Hexagon Constellations
Happy December!
No, that is no oxymoron as this month is crammed full of celestial delights, not least of which is the Winter Hexagon, the bright assortment of stars defining the circumference of an irregular hexagon.
Since the first part of our night sky calendars now focuses on the stars, today we're going to run around the Winter Hexagon and explore three of its constituent constellations.
ORION THE HUNTER recently reappeared in our early evening sky. His return doesn't occasion him the same ecstasy that so profoundly affects the rest of us. After all, Orion has been milling about the sky for more than a century of centuries: he loomed high in the firmament when the Stonehenge builders convened their first meetings on the English plain; looked upon the flames and revelry of Rome's Saturnalia festivals; was largely ignored by the Bayeux tapestry weavers; revered by Doctor Faustus; studied by Thomas Jefferson and observed by Harry Potter. And, he lingered about thousands of years before Stonehenge was merely a blue print just as he will be traipsing through the heavens centuries after Harry becomes a figure of ancient literature. To Orion, this most recent return is just the latest go around in an interminable circuit through Earth's skies. (As Orion's stars are quite distant, he is likely poised high above many nearby alien planet scapes, as well.)
Tonight, Orion will have completely risen by 7:30 p.m. One can find the grand hunter on its side, as though in repose, just above the eastern early evening horizon.
A large rectangle enclosing a diagonal three star belt comprises his main pattern. Two star lines curling out from his northeastern rectangle star, Betelgeuse, form a bronze club. A semi circle of stars surrounding the northwestern rectangle star, Bellatrix, represents a lion skin shield. A faint sword dangles from his belt. A solitary star marks his head.
Mythologically, Orion has assumed various identities: the Egyptian Death God Osiris; the grand Hebrew hunter Nimrod; the Sioux warrior Long Sash; and in some traditions was Feryja, a Nordic Goddess. One will find other Orion incarnations in various African, Asian and other cultural folklore around the world. Since the celestial equator -the projection of Earth's equator onto the sky- passes just above the belt, Orion is wholly visible to more than 99% of the world's population. (Only the chest and shoulder section appear around the North Pole; whereas a South Pole observer sees only the belt and legs.) His widespread visibility, his stark resemblance to a standing human, and his collection of brilliant stars have assured Orion a global fame surpassing that of any other single star pattern.
ORION THE HUNTER: The grand hunter looming large over the winter evening sky. Two of its brightest stars, Betelgeuse and Rigel, are parts of the Winter Hexagon. Betelgeuse marks the center and Rigel the southwestern vertex of this famous hexagon.
Of all his other identities, he is now principally known as Orion, considered the greatest hunter in Greco-Roman mythology, superior even to Artemis, Goddess of the hunt and the Moon. One tale portrays Orion as reckless and boastful. So proud was he of his hunting prowess that he openly proclaimed himself capable of slaying any beast, no matter how formidable. Appalled by Orion's impertinent attitude -such irrational arrogance was only deemed proper in Olympus- Artemis deployed Scorpius the Scorpion onto Earth. The Scorpion promptly found Orion and nipped his ankle, killing him instantly. Curiously, Artemis then foisted Orion's spirit into the sky and bejeweled him with bright stars as a tribute to his superb hunting skills. He was perhaps also set into the stars as a warning to other gifted mortals that it is best for one to remain quiet about one's exceptional abilities.
And there he remains on full display as he has for such a long time. We should point out that even Orion is ultimately mortal. His component stars all move through the galaxy in various directions and after tens of thousands of years, the pattern will become noticeably distorted and ultimately unrecognizable. For us mortals, Orion's life is interminable. However, by galactic time periods, Orion is a fleeting configuration: just one of the myriad star patterns through the galaxy that form and dissolve in deep time.
CANIS MAJOR
CANIS MAJOR: "The Great Dog" Trailing behind Orion
the Hunter, Canis Major is often depicted as one of
Orion's hunting dogs. Canis Major's brightest star, Sirius,
is also the brightest star in the night sky. Image: Allthesky.com
The story of Canis Major involves something highly unusual: a mythological paradox. The story begins with something that's not so unusual: Zeus lusting after a woman. Zeus was enamored of the beautiful Europa, who was descended from Io who, not surprisingly, was also once desired by Zeus. In this latest tryst, Zeus transformed himself into a gorgeous white bull who appeared to Europa while she was gathering flowers. Unlike most bulls, this one behaved in a gentle manner and, apart from inspiring fear, attracted Europa. While the hapless woman was adorning the bull's horns with flowers, she was promptly whisked away by the bull into the sea. While still in the form of a bull, Zeus spirited Europa across the ocean to Crete. Once there, Zeus and Europa conceived King Minos.
During their time together, Zeus presented Europa with Laelaps, a dog so swift it could catch any prey it pursued. Europa gave this dog to her son, who found little use for it, apart from his own amusement. Years later, Amphitryon kidnapped this dog in the hope that it would capture the Teumessian fox, which had been terrorizing the citizens of Thebes. Dionysius sent this fox to Thebes to punish its people for its lack of "reverence." Dionysius was known for being a bit thin-skinned. The problem was that this divinely gifted fox could elude any predator. The clever Amphitryon knew that Laelaps could catch any prey, so it would be the only creature capable of capturing the Teumessian fox. Alas, a paradox ensued as the animals raced around the land, the uncatchable sought by the unavoidable. Zeus intervened and resolved the paradox by first transforming the fox and dog into stones and then casting them into the sky as Canis Minor (fox) and Canis Major (dog). In this way, the dog has the fox in its sights, but can never actually capture it.
Sirius marks the great dog's throat. Although it is the night sky's brightest star, it is not the closest to our solar system. Eight stars, including Proxima Centauri, Wolf 359 and Luyten 726-8A, are closer. With a luminosity 25 times greater than the Sun's, Sirius is intrinsically brighter than these closer companions and therefore appears brighter in our night sky.
CANIS MINOR
"The lesser dog." A 1801 image in Johann Bode's
Uranographia. The obedient dog looks up admiringly at
Orion the Hunter. Image: Alesso Govi
A common tale centering around the two dogs involves their master, Orion the Hunter, whom they obediently follow across the sky. While Orion is embroiled in a violent fight with the fearsome Taurus the Bull, the hunting dogs pursue the gentle Lepus, the hare who is seen sprinting away from the dogs just south of Orion. Although a hare wouldn't last long when confronted by such formidable predators, Lepus maintains a safe distance from the pursuing dogs. Though perpetually fearful and condemned to always flee from its attackers, Lepus will always remain safe and sound in the stars.
The calendar continues tomorrow.
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