THE USM SOUTHWORTH PLANETARIUM

207-780-4249     www.usm.maine.edu/planet

70 Falmouth Street     Portland, Maine  04103

43.6667° N                   70.2667° W 
Altitude:   10 feet below sea level

Founded January 1970

Julian date:  2458661.5

             "Heavens below!"

THE DAILY ASTRONOMER

Thursday, June 27, 2019

Four Point Menagerie

We balk when some people describe the sky as the "celestial zoo," for the heavens are the playground of the free and unfettered.  Animals abound, of course, but in the wide open spaces.  It's a menagerie, far removed and high above terrestrial constraints.  These beasts and beauties adorn our sky just as they have for centuries.  In fact, we believe the ancients established constellations as a means of tracking the seasons:  certain patterns visible in the winter evening are absent in the summer and vice versa.        Today, we focus squarely, or, perhaps circularly, at four animals, each of which occupies a cardinal point in early evening.     While one of these creatures, Ursa Major, is circumpolar and always in our sky, the other three, Leo, Scorpius and Delphinus, rise and set: prominent in certain seasons, but all but lost for at least two months each year.

We take them in turn:


URSA MAJOR: The Great Bear
By Till Credner - Own work: AlltheSky.com

URSA MAJOR, THE GREAT BEAR
Northern circumpolar constellation
Those with disturbed souls will often use the terms "Big Dipper" and "Ursa Major" synonymously.   In fact, the Big Dipper, an asterism, is part of Ursa Major.    The dipper's bowl represents the bear's mid section; the handle marks its extraordinarily long tail.   The Great Bear Ursa Major, and her companion, Ursa Minor (the little bear) are circumpolar and therefore always in our northern sky.    One might note Ursa Major's gender:  female.    Mythologically, Ursa Major was once a beautiful huntress named Callisto, who spent her days pursuing game with her only son, Arcas.    Unfortunately for Callisto, Zeus, the king of all gods and other licentious wretches, spied her running merrily through the forest.   He desired her intensely and was determined to seduce her. Well, Hera, Zeus' long-suffering wife, was aware of Zeus' lustful intentions and decided to curtail his latest mis-adventure.   She transformed the innocent Callisto into a giant bear, at which point, admittedly, Zeus became discouraged and lost interest.  Cruelly, Callisto retained her human mind and soul, and, horrified at her transfiguration, fled into the deep forest.     Soon after, Arcas, who had been seeking his mother ever since her abrupt disappearance, wandered into a grove where Callisto had been sleeping.    She awoke to see her son and, forgetting her new ursine form, ran to embrace him.   Arcas, seeing what he thought was a bear in angry pursuit, withdrew an arrow to slay it.  At this point Zeus intervened.   He transformed Arcas into the little bear, grabbed them both by the tails, and flung them into the sky.    This violent propulsion stretched their tails.   While Hera did nothing more to torment them, she did ask Poseidon, God of the Sea, to deny them sleep and bathing, so they could never descend below the horizon.    Despite these discomforts, the Great and Little Bears happily chase each other around the northern sky.    See them in the depth of summer, the core of winter, or the outer convective layers of autumn and spring.

Leo the Lion

Image by www.starrynight.com

LEO THE LION Western early evening sky

Leo is not long for the world.  The Sun "enters" Leo in mid August and therefore is now very close to the setting Sun.   Leo is the prominent spring constellation, so named as it remains visible throughout the spring evening sky.     In mid summer, Leo prepares for its brief departure.     Seen as a lion for more than five thousand years, Leo has assumed various identities: most notably that of the Sphinx and of the Nemean Lion.   The latter was the particularly vicious lion who had a taste for human flesh and indulged itself at every possible occasion,  Attempts to slay it were in vain, for nothing could penetrate its hide, apart from its own claws.    Moreover, it was ten times larger than the next largest lion and struck terror into all who encountered it.    It was left to Hercules to slay Leo, as part of his famous twelve labors.  He was made to perform these labors to atone for the slaying of his wife and children under Hera's bewildering spell.   After he exhausted his quill of arrows and saw they were ineffective against Leo, Hercules wrestled with it and eventually prevailed.  He strangled the Lion and then used its claw to cut away the hide that he then used as a shield throughout his many subsequent adventures.    Hera placed Leo in the sky, as a tribute to its formidable power and as a reward for making Hercules' life so difficult.

Scorpius the Scorpion

Image by Bob Moler

SCORPIUS THE SCORPION
Southern evening sky

We call Scorpius a Southern Hemisphere constellation because it is quite high and prominent south of the Equator.   However, we can see observe it in its entirety here.  In fact, the mid latitude region marks the northern most region where one can still see the entire Scorpion pattern.     Venture even a short distance north and you'll find that the southern horizon will cut off its curling body.     Like Leo and unlike many other constellations, Scorpius resembles its namesake.  Its head and claws are attached to a descending arc of stars representing a body and lethal stinger.    Mythologically, Scorpius is associated with Orion the Hunter.    Orion was a boastful hunter whose prowess became legend.   Believing his own press, Orion once recklessly proclaimed that he could kill any beast in the world.  Moreover, he said in a lamentably loud voice that he would certainly be known as the best hunter once he actually did kill every animal.    This claim horrified Diana, goddess of the Moon and wild animals.  Fearful that the insolent Orion would make good his boast, she crafted Scorpius out of fire and soil and then deployed him down onto the world to seek out Orion.      The scorpion found the hunter quickly, as it just followed the path of cadavers Orion had left.   Without so much as a villainous monologue for effect, Scorpius nipped Orion's ankle, killing him at once.     Both the scorpion and Orion were hoisted into the stars: the former as a reward for his dutiful service, the latter as a tribute to his hunting abilities.  Diana was also said to have been in love with him.  Go figure. 

 
Delphinus the Dolphin
Image by Naoyuki Kurita

DELPHINUS THE DOLPHIN
Eastern evening sky

It is called the 'jewel box,' for it is compact and beguilingly beautiful.     Delphinus the Dolphin is one of the night sky's hidden treasures: best seen when observed along one's periphery.  We call it 'averted vision,' the technique of enhancing an object's brightness by viewing it off to one's side.  (This method works because the side of our eye is more sensitive to light than the front.)     This star pattern appears as a dolphin that has just emerged above water.    
Delphinus was the dolphin who saved the divinely gifted musician Arion, not to be confused with that hunky thug, Orion.    Arion recently won a sack of gold in a music competition held in Crete.    The sailors who conveyed him to this competition, and were hired to deliver him back home, conspired to abduct him if he won the gold.   Actually, they knew he would prevail and made plans for his kidnapping all along.   As soon as the boat left Crete after the competition, the sailors captured Arion and stowed him below deck.      They then took Arion's gold and resolved to kill him and throw his body into the sea.    The sailors rapidly brought him on deck, backed him up to the side of the ship and encircled him.  Knowing his was doomed, Arion asked them to allow him to perform one last time before he died.  The sailors consented, for they all actually loved his music.   They handed Arion his lyre, which they had also confiscated, and he played.   His song was so lovely the sailors were reduced to tears.   They also summoned forth dolphins who swam up to the ship to be close to the music.   As Arion played, he looked over the ship's edge and saw Delphinus looking up at him.    In an instant, Arion tossed himself over board. He climbed on Delphinus who then spirited him away to safety,    For his service to Arion, Delphinus was honored with a place among the stars.


Four points. 
Four animals.
Four ancient stories that still play themselves out over our modern world.

We'll lose Leo by the end of July. Scorpius will remain in our evening sky until October.  Delphinus dives below the horizon by mid winter.
Ursa Major always remains with us...

Seek out the four point menagerie this evening. 
But whatever you do, don't call it a "zoo."