THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland,Maine 04103
(207) 780-4249 usm.maine.edu/planet
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
2021-2022: XXXIII
"Give me a lever long enough and a fulcrum on which to place it, and I shall move the world."
-Archimedes
THE DAILY ASTRONOMER
Wednesday, October 20, 2021
Splintering the Argo Navis
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Happy Birthday, "Alpheratz"
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Although the thoughts of warmth-deprived northerners tend to drift longingly toward the southern climes around this time of year, we often neglect to consider the impressive array of stars adorning the southern firmament. After all, it is exceedingly difficult to think much about the constellations lurking below the horizon.
Today, we'll be less northern-centric and look upon the vast region once known collectively as "Argo Navis," and now seen as three separate constellations.
MYTHOLOGY ALERTJason, one of the mythological realm's most celebrated heroes, was charged with the daunting task of retrieving the Golden Fleece. This gilded fleece was shorn from the zoologically improbable winged ram Chrysomallos. The characteristically convoluted (but deliciously interesting) backstory involves King Athamas, legendary founder of Halos, who fell in love with and married Nephele, a beguilingly beautiful cloud nymph.* Athamas sired two children on Nephele: Phrixus and Helene.
Life was proceeding swimmingly for the couple and their children until Athamas became enamored of Ino, the daughter of Cadmus, the founder of Thebes. This infatuation soon became so consuming that Athamas started to ignore his wife. Understandably chagrined by this neglect, Nephele left her husband and returned to the upper troposphere to seek solace among the cumulonimbus. Her nebulous nymph cohorts were deeply sympathetic to the heart broken Nephele and conspired to punish Athamas by withholding all rain from his kingdom.
Troubled and perplexed by the sudden drought,** Athamas sought counsel with his new wife, Ino. Ino, we must mention, hated her stepchildren as she was jealous of her husband's love for them. (Although the king became appallingly caddish toward his wife once he fell in love with Ino, he never became cool to his children.) Ino convinced her husband that he had to sacrifice his children to their mother in order to end the drought. "She wants them with her now that she can't have you," she argued. While someone less love-besotted would have questioned her logic, Athamas agreed with Ino at once and miserably resolved to sacrifice his children the following morning.
That night Nephele appeared to both her children in a dream. Accompanied by a beautiful golden ram sired by Poseidon onto the nymph Theophane, *** Nephele told her children that their father was intending to kill them at dawn. She assured them, however, that she would send the ram down to Earth to rescue them. Curiously, she also told them not to bear any grudge against their father, whose senses Ino had bewitched.
The following morning, as the distraught, sword-wielding king hovered over his children, the golden ram swooped down and spirited them away. During their journey to Colchis, Helle fell to her death into the ocean below. (The Hellespont, now known as the Dardanelles, was named for her.) Phrixus was conveyed safely to his destination. Once in Colchis, he took refuge in the house of Aeetes, son of Helios. He placed the golden fleece he took from the ram into an oak grove sacred to Ares. There, the unsleeping dragon guarded the beautiful gilded fleece.
It was this fleece that Jason and his merry band of warriors sought and -spoiler alert- eventually captured despite the insomniac dragon. Jason and his formidable pack of cohorts, including Castor, Pollux, Orpheus and, briefly, Heracles, embarked on their daring quest aboard the Argo Navis, hence the phrase Jason and the Argonauts.
The constellation Argo Navis was the largest of the 48 constellations Claudius Ptolemy (c 100 - 17o AD) included in his famous catalog. At the time, the stars comprising the ship were visible from the area now known as Greece. However, precessional motion, the "wobbling" of the axis resulting principally from solar and lunar gravitational influence, has caused most of those stars to set. Consequently, the constellation well known to antiquity is largely hidden from modern-day mid-latitude observers.
Then again, the Argo Navis no longer exists, anyway, at least not as a single constellation. When charting the sky, Uranographers, the astronomical equivalent of cartographers, found Argo Navis to be far too unwieldy as it was nearly thirty percent larger than the second largest constellation.
Finally, in 1755 French astronomer Nicolas Louis de Lacaille (1713-1762). divided the Argo Navis into three distinct constellations: Vela (the sails), Carina (the keel) and Puppis (the poop deck). However, the whole Argo Navis remained intact on other star charts, generally in deference to Johannes Bayer (1572-1625), who produced the revered Uranometria which included the entire ship as one constellation.
Nicolas Louis de Lacaille (1713-1762)
The first astronomer to break apart the Argo Navis
Finally, in 1930, the International Astronomical Union, which apart from governing the tides and maintaining the integrity of the time stream against causality violating Daleks, is responsible for all official celestial designations, settled the matter by listing Carina, Vela and Puppis as separate constellations. They designated the great Argo Navis constellation as obsolete.
And, to this day, the magical craft that once conveyed Jason and his Argonauts to fetch the golden fleece remains detached, a splintered wreckage consisting of keel, sail and poop deck, all of which would sink and be functionless if in isolation. Oh, well. Even when it was intact, the Argo Navis sailed backward due to the retrograde rotational motion of the southern hemisphere's sky.
Splintering ships, boats sailing backward and stars that ultimately sink out of our view. And, to think that we could ever refer to such a dynamic starfield as a "static night sky."
*The mythological realm was a veritable festival of nymphs, dryads and other lesser divinities who nestled in tree canopies, glided along wind gusts, bathed in remote pools, reclined along verdant meadows and floated within clouds. Though quite peaceful by nature, they could be provoked to violence by anyone who defiled the object with which they were associated. As we'll see in today's mythological story, they also didn't particularly like it when their spouses developed infatuations with others.
**Really? You cheat on your cloud nymph wife and a sudden drought confuses you?
***And, speaking of convoluted: Poseidon carried the stunningly gorgeous Theopane to the island of Crinissa and transformed her into a sheep. He turned himself into a ram and in that form made love to Theopane and conceived the golden ram.
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