*[image: tmp636370900286963714.jpg]*
*Ceyx and Alcyone:  * Dangerous terms of endearment*. *
The mythological Lucifer was nothing like the Lucifer with which most of us
are familiar.    Lucifer, whose name means "light bringer," was the son of
Aurora, the dawn goddess and her lover Cephalus.   Lucifer matured into the
radiantly beautiful young man who often shone like a brilliant star*
against his mother's ethereal light.    Having been known as a demi-god who
rarely strayed away from his adoring mother, Lucifer figured little in the
mythological sagas.   He is perhaps best known for having sired Ceyx, one
half of the ill-fated couple Ceyx and Alcyone.      Alcyone was the eldest
daughter of Aeolous, the king of the high winds.     One day as she was
gliding along an early morning ocean gust, Alcyone caught sight of Ceyx,
who was running along the east in full view of his adoring father.
 Alcyone had never before seen such a lovely young man.  (He was nearly as
radiant as Lucifer.)    When Ceyx caught sight of her, he, too, was so
enraptured that he stopped running and remained still merely to admire
her.  Without speaking a word, Ceyx and Alcyone approached one another and
embraced.    Within an instant, they fell passionately in love.   Theirs
was the unusual type of love that intensified with time instead of
diminishing.    Neither Lucifer nor Aeolous voiced any objection to the
union.   If they had had any misgivings, they decided it would have been
pointless to have expressed them as Ceyx and Alcyone seemed to have one
soul between them and could not be parted from one another.

Ceyx and Alcyone were soon married and lived happily together in Trachis, a
region in Greece south of the River Spercheios.   Keenly aware of both
their exalted status and blissful marriage, they chose the loftiest terms
of endearment possible.   Alcyone often referred to Ceyx as "Zeus," and
Ceyx, in turn, called Alcyone "Hera."      When they came to learn of this
practice, the real Zeus and Hera were incensed.   (The other gods secretly
thought it amusing that such a loving couple could have compared themselves
to Zeus and Hera, whose marriage was -to be charitable- disastrous.)   Zeus
resolved to punish them both for their impertinence.   For many nights,
Ceyx dreamt of frightful monsters who had emerged from a chasm and devoured
Alcyone.  These night visions inspired such horror in him that Ceyx decided
to travel to Delphi to consult the famous oracle.  When Ceyx spoke to
Alcyone of his intentions, she was terrified, for the journey would require
sea travel, which most dreaded,       "Let me accompany you, dearest
husband," she pleaded.    "I shan't be gone for long," Ceyx assured her,
perplexed by her earnestness.   "I need to seek out the oracle, something I
need to do alone."  Despite Alcyone's persistence and his own deep desire
to have her accompany him, Ceyx did not relent.  He felt that the trip
might prove perilous and he did not want to jeopardize Alcyone.

Ceyx and Alcyone passed a sleepless night prior to Ceyx's departure.  They
were miserable at the prospect of being apart even for a brief time and
spent the night locked in each other's arms.   The next morning as Ceyx
prepared to embark on the ship, he told Alcyone that he would return soon
and, in the interim, would often visit her in her dreams.     Alcyone
begged one last time to accompany Ceyx,, but he refused to permit her to do
so.    Ceyx boarded the ship without another word.    Soon after, the ship
was making great progress due, in large part, to Aeolous' favorable winds.
 However, one evening a blinding lightning bolt ripped through the sky and
struck the ship.    The ship's crew panicked as they watched their vessel
catch fire and rapidly sink.    Ceyx, alone, remained calm. He yielded to
death with stoic resignation, gladdened that Alcyone was safe at home, far
away from danger.  He uttered her name silently as the waves engulfed him.

To Alcyone, every day that elapsed without Ceyx passed as slowly as a
year.  She eagerly awaited each night, for she hoped to see her husband in
her dreams.  Yet, she never did.    Her sleep was both disturbed and
dreamless. Each morning she awoke and prayed  to Hera, her matron goddess,
to protect her husband and, in time, conduct him safely back to their
home.  Though like her husband, Hera, too, was displeased at the way Ceyx
and Alcyone used their names, she was finally moved to pity.    Ceyx had
been dead for many days and Hera thought it time to inform his widow of
what had transpired.  She instructed Iris, the goddess the rainbows, to
travel to the dark realm of Somnos, the god of sleep.   Iris was to ask
Somnos to tell his son, Morpheus, the god of dreams, to inform Alcyone of
Ceyx's passing.  That night, as Alcyone slept, Morpheus visited her
disguised as Ceyx.    Alcyone screamed at the sight of her husband covered
in ocean water and seaweed.  "I am dead, Alcyone," the dream Ceyx told her
solemnly.  "I perished many nights ago and even now my body floats along
the sea surface.    Weep for me so that I shall not pass into the
underworld unmourned,"   As Ceyx reached out to touch her hand, Alcyone
awoke.  Though the sky was still dark, she rushed down to the same point
along the sea shore where she had watched her husband depart.        She
sat there looking forlornly at the ocean water hoping in deepest earnest
that Ceyx was still alive.      Soon after the sun rose, she saw something
floating on the water toward her.     When the object came close to the
shore, she saw that it was Ceyx's body.  She wailed with grief and decided
to dive into the ocean and end her life.    However, before she touched the
sea surface, her body was transformed into a kingfisher.   Instead of
swimming, she was gliding along the ocean surface.  To her delight, she
realized that Ceyx, as well, had also undergone a similar metamorphosis.

[image: March2017_0327c.jpg]

The two Kingfishers then ascended high in the air.    They spent the day
playfully chasing each other and calling to one another in a secret
language only they could understand.      Each year these Kingfishers
conceived a brood of hatchlings over which Alycone maintained a constant
vigilance for seven days around the winter solstice.   During this week,
all the water-disturbing winds subsided at the behest of Alcyone's father.
 The turbulent ocean was replaced by a sedate sea and for those seven days
it seemed as though the entire world lay unperturbed.   The hatching eggs
would then shatter the tranquility, putting an end to that serene period
around the solstice named for Alcyone and popularly known as the "halcyon
days."

*The planet Venus

THE SOUTHWORTH PLANETARIUM
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Julian Date: 24591167.16
2020-2021:  XLV

THE DAILY ASTRONOMER
Monday, November 16, 2020
Remote Planetarium 124: Dark Energy I


We begin today with an extraordinary premise:   the Universe expands.
This expansion started just after the cosmic inception, approximately 13.8
billion years ago.    Humanity has known of this expansion for less than a
century.  Prior to this time, we perceived the cosmos as either being
stagnant or eternal without any beginning at all.      Now, cosmologists
widely accept that the Universe began in a single event -the Big Bang- and
has been growing ever since.

The question then becomes, what is the Universe's fate?    Will the
expansion slow down and stop?  Will the expansion slow down, stop and then
reverse to cause a *Big Crunch,* the implosion of everything?  Or, will the
expansion literally continue forever?  The answer to that question once
seemed to depend solely on the material within the cosmos.    Did the
Universe contain enough matter to retard the expansion through
gravitational breaking?  Would this deceleration then cause the Universe to
either stop (a flat Universe) or reverse course (a closed Universe)?   Or,
was it insufficient and the Universal expansion would persist indefinitely
(an open Universe.)      The entire issue was predicated on the assumption
that the expansion rate would decrease with time.     Cosmologists tried to
ascertain if the Universe's density was less than, equal to, or greater
than the critical density.

[image: univcurv.gif]
*The three "fates."  *Once astronomers realized that the Universe was
expanding, the only question remaining pertained to its fate.   Would the
expansion stop and precipitate a collapse?  Would the expansion stop and
cause the Universe to become static?  Or, would the Universe continue to
expand forever.       The answer to that question was once believed to be
related solely to Universe's material density:   was the density sufficient
to halt the expansion?   With the inclusion of dark energy, we know now
that the issue is far more complicated.

In the late 20th century, this fundamental cosmological question became far
more complicated.     A 1998 Survey conducted by two astronomical teams*
showed that Type Ia supernovae which exploded when the Universe was about
9.2 billion years old (2/3 its current age) were much fainter than they
should have been.  The only conclusion to be drawn from this observation is
that they had to be much farther away.            Type Ia Supernovae occur
when a white dwarf star draws so much material away from a larger companion
that it exceeds its C-limit and explodes. (See the caption under the next
graphic for more information.)     Any Type Ia Supernova should be as
bright as any other, which makes such supernovae useful to astronomers for
distance determination.      If one knows the object's intrinsic
brightness, its distance can be readily determined by measuring its
apparent brightness.

[image: supernova-type-1a_1280.jpg]
*Type Ia Supernovae *occur when a white dwarf strips material away from a
much more massive companion.  If it collects enough material, the whitre
dwarf will explode to create a Type Ia Supernovae.   To understand why this
explosion occurs, we must first examine a white dwarf.    A white dwarf is
a dense remnant created when a low-mass star exhausts its core fuel
reserves.    It casts off its outer layers as a planetary nebula and leaves
behind a highly dense white dwarf core.  Despite the lack of internal
energy pressure, this white dwarf doesn't collapse because of electron
degeneracy:  the electrons within it prevent further collapse due, in part,
to electrostatic repulsion. (The electrons resist each other due to their
like charges.)     This electron degeneracy will withstand the white
dwarf's gravitational compression provided the remnant's mass doesn't
exceed the Chandrasekhar limit, equal to about 1.44 solar masses. (1.44
times more massive than the Sun.)   If the white dwarf's tidal forces draw
enough material onto it so that its mass exceeds the Chandrasekhar limit,
it will collapse and explode as a Type Ia Supernova.

They concluded that the Universal expansion was accelerating, not
decreasing, with time.  The teams also realized that the expansion had
decelerated for the first eight billion years after the Big Bang. Then,
inexplicably, the acceleration started and still continues.     The term
applied to the force responsible for this phenomenon was called *dark
energy.  *Unlike "dark matter," in which the dark refers to a lack of light
emission, the "dark" in dark energy refers to our ignorance of it.
 Scientists know very little about this mysterious force.  They don't know
how it can cause such an acceleration or if it will even continue.

It has been suggested that dark energy might be related to Albert
Einstein's "cosmological constant."  We recall that Einstein inserted this
constant into his theory of General Relativity in order to counteract the
expansion inherent within them.   At the time of GR's formulation, Einstein
considered the notion of an expanding Universe to be preposterous.      He
would later refer to the cosmological constant's introduction as the
"greatest blunder of my life."     Is it possible that this "fudge factor"
might be real:  that some anti-gravity force is pushing the Universe
outward at a much greater velocity?

Though Dark Energy's nature remains unknown, cosmologists estimate that it
comprises about 68% of the Universe.     Since dark matter is thought to
account for 28% of the cosmos, one can conclude that only four percent of
the Universe consists of visible, baryonic matter such as stars and
galaxies.       A sobering return to the ancient days in which most of
nature was relegated to the mystical realm.

Tomorrow, we continue this dark energy exploration by learning how
scientists might be able to observe it or at least learn more about it.

*These teams included Saul Perlmutter, Adam Riess and Brian Schmidt, all of
whom won the 2011 Nobel Prize in Physics for the discovery of the
acceleration of the Universal expansion.

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