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

_____________________________
Happy Birthday, "Alpheratz" _____________________________

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.

                      [image: Argo_Navis_Hevelius.jpg]

[image: Action-Alert-symbol.png] *MYTHOLOGY ALERT*
Jason, 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.


[image: 375px-Lacaille.jpg]
*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.


To subscribe or unsubscribe from the Daily Astronomer:
https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=
<https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=1>