[image: Medusa-marble-sculpture-Gian-Lorenzo-Bernini-Capitoline.jpg]
*Medusa: The Unseen *
We loathed you for your malignity, shunned you for your ugliness; detested
you for the slain multitude you have left in casts of stone; and we
celebrated your beheading at the hands of the heroic Perseus. What we
did not do is understand you. We did not understand that your malignity
was grief; your ugliness a punishment, your powers a curse and your
slaughter a wanton murder authored by the very goddess who made you the
monstrosity that, lamentably, now defines you. Since we're encountering
you during our astronomical excursion, we should strive to see you.
Not the gorgon Medusa writhing in anguish upon the remote, barren island,
but the woman Medusa who traipsed into Athena's temple at the summons of
Poseidon, the one she was audacious enough to call her "lover." The same
Poseidon who governed the dark, tide torn sea and stood steadfast against
the myriad creatures seeking to undermine his reign. Unlike the morose
Hades who merely collected the shades in Asphodel or the grand Zeus of the
boundless skies, Poseidon remained in perpetual conflict with the very
domain of his sovereignty. It was due to the relentlessness of his duties
that he devoted precious little time to the young woman who was deeply
devoted to him. Such has it been since their 'love affair" began when she,
as a young girl, spied the ocean god in the company of his sea nymphs and
became instantly enamored. As she was so young and beautiful, Poseidon
consented to visit her upon occasion. The naive Medusa regarded these
infrequent visitations as evidence of requited love. She retained this
delusion on that beautiful night when Poseidon looked upon Medusa despairing
in Athena's temple. She went there and waited, despite being afraid, for
she felt that her presence was an unpardonable intrusion. She had set her
fears aside because she was compelled by the one force that has always made
a forfeit of our reason and driven us to actions that are usually
irrational and frequently unforgivable: love. Mind you, this was not
just any love. This was the love for an Olympian God and therefore
destined to rapid dissolution. Yet, that frail, but resolute,
beautiful, but star-crossed, mortal woman could not have known the
consequence of this folly. In that Athenian temple on that beautiful
night Poseidon came upon her in the magnificent human form he assumed on
Earth. For you see, Poseidon was not human. When in his natural
state, he was the greenish gloom of ocean water; just as Zeus, in his
undisguised state, was a thunder cloud. Poseidon sensed Medusa's sorrow
when he approached her. It was to his consternation that she could not
at first look at him. She avoided his eyes even as he stood before
her. When he spoke, in the strangely dulcet yet commanding tone particular
to Olympians, and inquired as to her sadness, she initially only shook her
head and looked away. Yet he persisted so that she finally did regard him
tearfully. declaring that her anguish was in her youthfulness and beauty.
For, it was these that Poseidon adored and not Medusa herself. He
loved her comeliness and vitality; a loveliness that he had described as
beyond that of any mortal rival. Yet, these would, in time, diminish in
his eyee. She was mortal and would not always possess the physical
aspects that Poseidon cherished.
"You love me for who I am, and cannot love me for what I will
become."
Poseidon laughed. "As you love me, dearest Medusa, for who I
am in your presence: mortal man made perfect. You say my love for you is
for a beauty you cannot retain, but your love for me is for an image that I
have merely conjured."
Medusa's tone became suddenly severe. Though compared to him she
was slight, Medusa reached up and cradled his face in her hands. The
stern girl stared into Poseidon eyes and said, "Then come to me aged;
come to me old, unsightly and enfeebled; cast away by a world made hateful
by its aversions and I shall nurture you in my lap and you shall never
know another cold, lonely moment."
Poseidon was perplexed into an uneasy silence. What a
silly, besotted thing she must have seemed to him. What effect could that
sentiment have had on a god? A being who could no more know the nature of
passionate love than he could know fear of mortal death. Since he knew not
how to respond with words, he responded with an embrace.
You know and I know what happened next. Words stopped and
passions were otherwise expressed. There, in the temple of Athena,
they engaged in what was once known as "bodily commerce." It would be
inaccurate to call it lovemaking, for such a term would be paying that
deceitful, manipulative, designing Poseidon more credit that he deserves.
It seemed to be lovemaking for the kind and earnest Medusa, a woman who
showed herself to be both strong and courageous, as opposed to frivolous
and pitiable. The weak and cowardly do not love as fully and face despair
as determinedly as Medusa did.
She never asked why Poseidon chose the temple for the sight of
their latest liaison. Even if she had, he likely wouldn't have told her
the truth. The truth being that he wanted their "commerce" to happen in
the very sight of Athena, the goddess of war and wisdom. He wanted Athena
to behold in full, clear splendor the body of a mortal woman whose beauty
was comparable to that of Athena herself. Thus, Athena saw Medusa and
Poseidon in the one place where neither belonged. But, of course, that
was part of the game which those vain and vicious Olympians played with
each other. Poseidon detested Athena and offered her a particularly
stinging insult. Athena would get her own back. Later, when Poseidon
returned to the turbulent seas, Medusa remained sleeping under the shadow
of Athena's statue, whose expression, once indifferent, soon became
menacing.
Medusa arose with her sleep with a start, aroused
by a searing pain in her stomach. She called out for Poseidon, but was
answered by silence. She stood, still nursing her stomach, and under the
silvered moon shone herself fully to Athena, whose fury took full form as
Medusa was at once transformed. Skin to scales; teeth to tusks; hands to
claws, tresses to serpents; woman to monster. Medusa gazed down at her
transfigured body and wailed to Poseidon to intervene, to restore her
beauty. Yet, she could not speak. Her pleads were guttural moans.
"Let us behold your beauty now..." the goddess
seethed while she watched the wretched Medusa stumble through the darkness
away from the temple and out into the sea beyond. She sank into the
waters, hopeful that perhaps Poseidon would be moved to pity and would wash
away this horrid curse. He didn't. He was then as he had been
before: indifferent. Now that she was deprived of beauty, he would see
her no longer. She swam to the island where the other two gorgons, Stheno
and Euryale, resided. A barren, atoll of rock far removed from the society
of men. There she spent day after day in the company of the only two
creatures in this "world made hateful by its aversions" that weren't
repulsed by her appearance. Though they were sisters, she was truly alone.
One might have thought that when the young and bold
Perseus, with the assistance and to the delight of Athena, herself,
traveled to the atoll and beheaded Medusa, she must have welcomed death as
a liberation.
It was only after her death that Poseidon, in a pointless spasm of
contrition, was curiously moved to pity: he took some of her blood,
spilling out of the satchel in which Perseus carried her head, and mixed it
with seafoam. From these two elements he fashioned Pegasus: the
beautiful, strong winged horse that became the embodiment of Medusa's true
nature: beautiful and free of the world. When Perseus ascended into the
ethereal heights and left his stellar imprint upon the celestial sphere, he
took with him Medusa's severed head: the grotesque trophy earned in his
youth. It has remained here over the centuries: a despised creature
amongst the retinue of heroes and ageless Olympians. When we first hear the
stories of Medusa, we are advised to never look at her directly. For this
reason, of course, we have never seen her clearly.
THE SOUTHWORTH PLANETARIUM
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Julian Date: 2459037.16
2019-2020: CLXXI
THE DAILY ASTRONOMER
Monday, July 6, 2020
Remote Planetarium 59: Intrinsic Variables II - Long Period Variables
[image: Cetus.jpeg]
Let's begin the week by discussing a star called "wonderful." Known by
the actual name "Mira," this star marks the long throat connecting the
faint head and larger body of Cetus, the seamonster. One can observe Cetus
in the early morning eastern sky this time of year. While seeing Cetus,
an observer might or might not find Mira because for much of the year it
won't be visible to the unaided eye. Its brightness varies from a
magnitude of 10.1 (minimum) to a magnitude of 2.0 (maximum.) When a
star's magnitude is 6.0 or higher, it generally isn't visible to the
unaided eye.
Mira is the archetype of the "Mira Variables," defined as those stars that
are passing through the latter stages of their life cycles. Their masses
are generally less than two solar masses. Mira variables are fusing
helium in their cores and will soon expel their outer layers as planetary
nebulae before leaving white dwarf remnants behind. Unlike Cepheid
variables that pulsate in response to helium ionization in specific layers,
Mira variables pulsate because the entire star is expanding and contracting
due to turbulent changes within the inner layers. This turbulence relates
in part to the motions of the hydrogen-burning shell enveloping the helium
burning core. Another difference relates to the substantial brightness
changes. Whereas a Cepheid variable's brightness diminishes and
increases as the size and temperature increase and decrease, the brightness
of a Mira variable will change as energy shifts from the visual to the
infra-red part of the electromagnetic spectrum. As Mira variables are
solar mass stars toward the end of their lives, they will actually be red
giants: much larger than the Sun, but also significantly cooler.
Also, recent observations have revealed that Mira variables tend to be
enshrouded in diffuse shells containing carbon dioxide, water vapor and
other molecules that will affect the star's apparent brightness.
Mira variables are distinguished by the following characteristics:
- periods between 80 - 1000 days
- masses comparable to that of the Sun.
- toward the end of their life cycles (Red Giant stage)
- the range of brightness variations can extend many magnitudes
Mira's variability period is 332 days. So, one can expect it to reach its
maximum brightness once a year. The following list includes the upcoming
dates of Mira maxima. Fortunately, the next Mira maximum occurs around
mid to late September, the time of year when its host constellation Cetus
is well placed for evening viewing.
*Mira Maxima:*
- September 20, 2020
- August 18, 2021
- July 16, 2022
- June 13, 2023
[image: Mira_light_curve.png]
The* "Mira Light Curve."* We see the variations in Mira's brightness
over time in the above light curve. Notice that the minima and maxima
are not consistent, but instead can vary by as much as a magnitude.
___________________________________________________
[image: Johannes_Hevelius(close-up).jpg]
Rapid astronomer profile: *Johannes Hevelius (1611-1687)*. Yes, we've
encountered him before. We saw Hevelius when we were discussing
constellations of relatively recent coinage. (He crafted a few of them,
himself.) Hevelius named the star "Mira," meaning "wonderful," because of
its tendency to appear and then reappear. He first included the name in
his 1662 publication "Historiola Mirae Stellae ," (A Short History of the
Wonderful Star.)
*_____________________________________________*
When at maximum brightness (magnitude 2.0) Mira is the brightest of the
Mira variables. The next brightest of *Chi Cygni, *a star within Cygnus
the Swan:
[image: Cygnus_constellation_map.svg.png]
*Chi Cygni *is marked by the black dot to the right of the vertical axis of
the "Northern Cross" which is just under Eta Cygni. Chi Cygni's
mean variability period lasts 408 days. At brightest, Chi Cygni's
magnitude equals 3.3. At its dimmest, the magnitude is approximately 14.1,
almost 1600 times dimmer than the faintest naked eye stars. Because the
variability period can itself vary by as much as forty days, we will not
post the same maxima calendar we produced for Mira. Besides, Chi Cygni at
maximum is three times dimmer than Mira at maximum.
The Mira-type is the main type of long period variable star. The only
other type is the "*semi regular variable*," those whose variability itself
varies considerably due to interior turbulence. Astronomers divide
semi-regular (SR) variables into four categories (a - d).
Perhaps the most famous example of a semi-regular variable is Betelgeuse,
the star marking Orion's eastern shoulder. (Orion isn't currently visible
due to its close proximity to the Sun.) Betelgeuse is also toward the end
of its life cycle and exhibits irregular variability due to a variety of
complex factors, including alterations in its magnetic field and the
conveyance of energy through its dynamic outer layers. In fact, just
within the last year we observed Betelgeuse's brightness diminish
considerably. Many of us wondered if that red supergiant star was about to
explode as a Type II supernova. It turned out that the dimming was merely
part of the irregular variability cycle and not a precursor to an imminent
explosion.
All long period variables, be they Mira-type or semi-regular, are stars
nearing the conclusion of their life cycles. It seems likely that
most stars will become variable at some point in these cycles: the type of
which depends, of course, on the star's mass. After all, a star's entire
life cycle depends on its mass.
Tomorrow, part three of our Intrinsic Variable lesson with Cataclysmic
Stars.
__________________________________
*Skywatching tip: Moon and Saturn*
Look for the moon near Saturn this evening! The moon still will appear
full tonight. The moderately bright "star" near the moon is Saturn, the
most distant planet visible to the unaided eye.
____________________________________
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