Niobe: A portrait of imperishable grief 

Do you remember Tantalus?   You know, the inexplicably wicked Lyrdian king who stole the gods' nectar and then became the most loathsome of dinner hosts by serving the gods his own son Pelops as the entree?   Zeus punished this extreme etiquette breach by tossing Tantalus into Tartarus where he languished for all eternity in a state of implacable thirst and insatiable hunger.    Yes, that Tantalus.      He also had a daughter, Niobe, who, happily, was not sauteed and served as her brother had been.     One might claim, however, that her ultimate fate was scarcely less horrible.        Having been the daughter of Tantalus and Dione, whose name literally means "goddess," Niobe naturally grew up to be a ravishingly beautiful young woman.     Though pursued by many suitors, Niobe chose Amphion, a son of Zeus, to be her husband.    Amphion was a world renowned musician who once helped his brother, Zethus, the Thebian king, build parts of the city literally with his music.   The stones were said to have moved of their own accord in response to his lyre melodies, much to the disgust of his ultra masculine brother who had to move the stones manually.        

Soon after her father was killed and condemned to Tartarus, Niobe and her new husband ruled Lydia together.    (Her brother Pelops, whom Zeus resurrected after Tantalus made a meal of him, had already left Lydia and conquered the region that was thereafter known as the Peloponnese.)     One could describe their union as bountiful. They sired seven boys and seven girls, all of whom were as flawlessly beautiful as their mother.    For many years Niobe and Amphion ruled Lydia, and then Thebes, wisely and justly.  Under their dominion both kingdoms prospered.    The king and queen reveled in their abundant wealth, the love of their many children, and the adulation of their subjects.   Paradoxically, these blessings brought forth in Niobe the mad arrogance that had proven to be her father's undoing.       During the 30th year of her reign Niobe was presiding over the annual festival celebrating Leto, the mother of Apollo and Artemis.   Having observed the throngs of admirers gathered before her, Niobe dispensed with the usual formalities and spoke out boldly,  "Why do we bother to revere and celebrate Leto, the goddess whom none here have ever beheld?   I stand before you now as I have stood before you for thirty years: as your queen and protector.    Burn the incense in my honor and that of my beloved husband whose harmonies rival those of the muses, themselves.    Sacrifice to me, the mother of fourteen and not to Leto, who sired only two.     Pay homage to me, your beloved liege, and not to Leto who was so reviled that only a floating island would give her refuge when needed to give birth to her only two children."   Appalled by Niobe's boldness and impertinence, Leto commanded Apollo and Artemis to punish the queen severely.    They both flew from Olympus to Thebes and swiftly slaughtered all fourteen of her children with arrows.    Niobe helplessly watched as her seven sons and daughters fell dead before her.    Her grief was said to have been boundless and for many days she wept inconsolably while the corpses of her children remained above ground.  On the ninth day, the gods, themselves, interred the bodies and Niobe remained rooted to the spot where she beheld her children's deaths.   Eventually she was transformed into a rock that was placed either under a snow shroud or next to a waterfall so that it was always wet, as though moistened by an unrelenting flow of tears.

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THE DAILY ASTRONOMER

Wednesday, May 13, 2020

Remote Planetarium 33:  The Sun's Structures

We would like to give you a homework assignment.    After you read today's article please walk to Los Angeles.    We understand that the separation distance might be considerable.   Any Portland (ME) resident, for instance, can expect a 3080 mile journey, give or take a few steps.      You might be closer or more distant.    How much time would walking such a distance require?   Well, depending on how often you decide to stop to wonder if the whole thing isn't just a little bit futile, the trip might require at least a few months.    The good news is that this jaunt to LA is merely part one of a two part exercise.   Once you reach Los Angeles, you must walk back to your starting point.   During your return journey, however, you must stop at every third house you encounter and enter it. (We'll give you a nifty mechanism that will enable you to unlock any door with just a casual wand wave.)   Once you enter the house, please sit cross legged on the floor and don't leave until the homeowner chucks you out.    As soon as you're ejected,  you must walk in the same direction toward which you were thrown until reaching the third house.    You would continue to infiltrate homes in various directions until you eventually reach your home city.      How long would this trip require?    Well, yes, just about forever.      Good luck.

What is the point of this exercise? Simply to enable one to appreciate the arduous journey the solar photons experienced before they scorched the beach sand or streamed through your window.   

The Sun generates energy in its core, where thermonuclear fusion reactions convert hydrogen into helium.   These reactions also transmute from the matter into energy.  The released energy "migrates" out of the core extremely slowly as each photon is absorbed and re emitted millions of times by intervening atoms .  The emissions can send the photon in any direction.     

We'll follow this photon during its journey:

CORE

Welcome to the Sun's hottest, densest and most active region.    Here one would experience temperatures exceeding 27 million degrees Fahrenheit and densities 150 times greater than water.     This is the only region in which thermonuclear reactions occur.  Every second the Sun "burns" 647 million tons of hydrogen to produce 643 million tons of helium.  The remaining material is converted directly into energy.   Astronomers estimate that the Sun has enough hydrogen reserves to sustain the hydrogen-to-helium reactions for the next five billion years.  Although the core's boundary is 0.2 solar radii from the center, the core's volume is only 0.8% that of the entire Sun. 

RADIATIVE ZONE

Here is where the arduous solar photon migration truly begins.    The gamma radiation streaming out from the core is absorbed and re-emitted over the course of nearly 300,000 years.   Consequently, the radiation that leaves the radiative zone runs the gamut of the entire electromagnetic spectrum.    We can count ourselves as fortunate as we certainly wouldn't be here if the Sun cast only gamma radiation into outer space.  

CONVECTIVE ZONE

What is the difference between the radiative and convective zones?   Well, convection, actually. 

The gases within the convective zone travel through convective cells that deliver heated material from the region just above the radiative zone to the upper areas where the material cools. The cooled gases, being more dense than its surroundings, descends back toward the radiative zone where it is reheated and then ascends again toward the upper regions.

Above the convective zone is the sun's upper regions, a highly complex area we will explore tomorrow as we conclude our tour of the Sun.

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