Laelaps and the Teumessian fox: A mythological paradox
Had I yielded to temptation and entitled today's mythological excursion "Dionysius and the Vixen," I would have horrified the delicate and inflamed the lustful, the latter of whom would have been profoundly disappointed to learn that the vixen was merely a fox. Known both as the Teumessian fox or Cadmean vixen, this gigantic animal was both a ferocious predator and, at the end, a beast at bay. In fact, the Teumessian fox was impossible to kill or capture. Little is known of its origin. Some say that it was sired by Zephyrus, god of the west wind, and a beautiful young woman, who, as a divine punishment for her liaison with Zephyrus, became monstrous and in time bore a litter of equally gruesome creatures. They all resembled gigantic and disfigured animals. Horrified at the appearance of her ghastly children, the unnamed woman promptly attempted to smother them all. Only one, the fox-like creature who inherited his father's swiftness, managed to survive. It escaped its mother's grasp and fled into the wild. His unfortunate mother, distraught at her own monstrous aspect and soon remorseful for the slaughter of her children, dissolved in a paroxysm of grief and became a willow tree. Such a tree's branches are said to bear a grief burden so heavy that even the wind's cheerful whispers cannot move them. 
The fox was said to have been a formidable hunter and sought prey wherever it lurked. Many people heard of this creature and a few even caught sight of it. However, any hunter who attempted to ensnare or kill it, failed. The fox ran from every one of its pursuers with a wind-like swiftness. At some point, Dionysius, the god of wine, spirits, and revelry, set it upon the people of Thebes to punish them for not having acknowledged that the mortal woman, Semele, conceived him with Zeus. Dionysius commanded the Teumessian fox to prey upon Thebes' children. He also endowed it with the magical ability to remain free of all constraints. The fox often snatched and ate unsuspecting children for it could appear out of nowhere and then vanish just as quickly. Every Thebian citizen feared this fox. Parents did not allow their children to venture outside lest they be consumed by this voracious fox. Creon, who was serving as Thebe's regent following Oedipus' abdication,* set the task of capturing the fox to his general Amphitryon, husband of Alcmene, the woman who would eventually become Hercules' mother.** Knowing that the fox could not be caught, the crafty Amphitryon somehow managed to
enlist the services of the hound Laelaps, who was capable of capturing everything it pursued. Laelaps was said to have been given to Europa by Zeus, who gifted her with the hound after he abducted her in the guise of a beautiful white bull. Just as Dionysius made it impossible for anything to catch the Teumessian vixen, Zeus made it impossible for anything to elude Laelaps. So, suddenly, the fox that couldn't be caught was pursued by the hound that caught everything it chased. It was left to Zeus to reconcile this mythological paradox, which he did by first transforming both the fox and the hound into stones. He then, for whatever reason, cast them both in the sky as Canis Major (the fox) and Canis Minor (the
hound). And, if you ask us, that is a lot of drama, intrigue, sweat, blood, toil, tumult and torment just to explain two small constellations.
*Yes, we remember that Oedipus ruled Thebes after having defeated the Sphinx. He then proceeded to marry this mother who was widowed when Oedipus unknowingly slew him on the road as he traveled to Thebes. (Well, Oedipus knowingly killed the man he regarded as a stranger, but didn't know it was his dad.) Of course, the gods knew that Oedipus had slain his father and married his mother. Consequently, the gods set a plague on Thebes that only lifted once Oedipus realized that he was married to his mother and had killed his father. He gouged
out his eyes and Jocasta, his mother/wife, killed herself. Oedipus relinquished the crown and eventually went into exile accompanied by his dutiful daughter/sister Antigone.
**But, Amphitryon was not Hercules' father! Zeus sired Hercules on Alcemene after he disguised himself as Amphitryon. That's another long story that can wait for another day.
hound). And, if you ask us, that is a lot of drama, intrigue, sweat, blood, toil, tumult and torment just to explain two small constellations.
*Yes, we remember that Oedipus ruled Thebes after having defeated the Sphinx. He then proceeded to marry this mother who was widowed when Oedipus unknowingly slew him on the road as he traveled to Thebes. (Well, Oedipus knowingly killed the man he regarded as a stranger, but didn't know it was his dad.) Of course, the gods knew that Oedipus had slain his father and married his mother. Consequently, the gods set a plague on Thebes that only lifted once Oedipus realized that he was married to his mother and had killed his father. He gouged
out his eyes and Jocasta, his mother/wife, killed herself. Oedipus relinquished the crown and eventually went into exile accompanied by his dutiful daughter/sister Antigone.
**But, Amphitryon was not Hercules' father! Zeus sired Hercules on Alcemene after he disguised himself as Amphitryon. That's another long story that can wait for another day.
THE SOUTHWORTH PLANETARIUM
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"When I stargaze I focus on the most distant star visible. Most people ignore it, though, because it is so faint as to be scarcely noticeable, like a candle flame in a far off window pane. That is what I seek while I lounge on the moist grass in the middle of the night. Though it is at the nether edge of my sight, I know that it is a blazing hot Sun that is setting over some being who will be looking for the most distant star in their sky, well beyond my view. That being, like myself, will yearn to peer into the depthless darkness behind it, into the endless succession of veils receding into the infinite."
THE DAILY ASTRONOMER
Thursday, September 3, 2020
Remote Planetarium 82: Galactic Survey II
Our whirlwind survey of the Milky Way Galaxy continues....
STARS! 300 billion
Heavens above, one cannot conduct a survey of the Milky Way Galaxy without counting the stars. They are the principal building blocks of any galaxy. According to recent estimates, our home galaxy contains approximately 300 billion stars. That value is quite impressive and, admittedly, well beyond all comprehension. How, one must wonder, did astronomers arrive at that value? They certainly didn't count them, did they? Absolutely not. One cannot conduct such a census on even a billion objects, let alone three hundred billion. Recall that one billion is an immensely large number. One billion minutes equals 1,901 years! Another problem with conducting a stellar census is our location. The solar system is tucked away within one of the Milky Way's spiral arms and so our view of some stars is blocked by gas and dust within the galactic plane. Astronomers refer to this obscured region as the "zone of avoidance." Since the stellar population is extensive and our view partially blocked, how can astronomers estimate the number of stars within our galaxy. They base this estimate on the galaxy's mass, which they can determine by its rotation rate. While the existence of dark matter complicates this measurement, astronomers know that the greater the mass the faster the rotation. They have determined that the galaxy's mass almost equals 1.5 trillion solar masses. (1.5 trillion times more massive than the Sun!) We know also that not all stars are of equal mass. Seventy percent of stars within the Milky Way are red dwarfs, the least massive of all active stars. Those were the stars that became just massive enough to ignite and sustain the core thermonuclear fusion reactions that power stars. Also, about 92.5% are main sequence stars, or type V dwarfs, like the Sun. The remaining 7.5% consist of giants, sub-dwarfs, white dwarfs and other types. Taking this frequency distribution into account, astronomers believe that our Milky Way contains about 300 billion stars!
PLANETS one trillion
The stellar census is admittedly quite uncertain. The planet population estimate is even more so. As of today, astronomers have confirmed the detection of 4330 exo-planets, planets in orbit around other stars. Based on these findings, astronomers estimate that our galaxy could harbor one trillion planets, forty billion of which revolve within their parent stars' habitable zones, regions where conditions could be conducive to life's formation. These estimates are quite uncertain still as the first exo-planet was only found twenty-five years ago. Throughout the next few years, astronomers will modify these estimates based on the number of confirmed exo-planet detections. They might decide the galaxy contains fewer or more than one trillion. Even then, they won't be certain.
BLACK HOLES one hundred million
Now, how could one possibly even come close to estimating the number of black holes in the Milky Way Galaxy?! Black holes aren't visible, are they? Well, unless a black hole is gravitationally linked with a stellar companion which will impart some of its gases around it to form a highly energetic accretion disk, it won't be visible. These estimates are based on the galaxy's pulsar count. Pulsars are the rapidly spinning neutron stars formed by the deaths of highly massive stars. Highly massive stars will also produce black holes, as well. Knowledge of the pulsar census leads naturally to an estimation of the black hole number within the Milky Way Galaxy. These estimates range from 10 million to a very high ceiling of one billion. However, the one hundred million value seems aligned with current observations of pulsars, the number of which could exceed 100 - 200 million.
GAS AND DUST: enough for more than a billion stars
When observing the Milky Way band in the sky, one can perceive dark patches against its light. These patches are cold, dark regions of gas and dust suspended within the galactic plane. Like most spiral galaxies, the Milky Way contains ample quantities of gaseous material from which future generations of stars will form. These nebulae will only condense into stars after they experience some sort of external disruption, such as the sudden shock of a nearby supernova explosion. These explosions will also impart vast quantities of metal-rich material into them, precipitating a collapse. In 4 -5 billion years, the Milky Way and Andromeda Galaxies are due to collide. This merger will compress many of these clouds within both galaxies, resulting in widespread star birth.
Next week, our galactic astronomy sequence continues....
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