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*Koalemos: the God of Stupidity*
So, a subscriber wrote to me the other day. "I'm a news junkie," he said
(or wrote). "I've been that way for years. Quite often, while watching
the news, I've wondered. 'Is there a Greek god of stupidity?' Can you
help?"
Yes, in fact, there is such a god. His name is Koalemos. One could
regard him as something of a minor deity....very minor. No cults formed
around his worship. No temples were ever constructed in his honor. He
inspired no battles, which is fortunate because his followers would likely
have lost them handily. He was such an obscure figure that he didn't seem
worth mentioning at all. However, the existence of Koalemos gives us an
opportunity to discuss these mythological figures and how they came to be
regarded as mythological. Classical mythology encompasses the works
numerous ancient world poets, notably Homer (the Iliad and the Odyssey),
Apollodorus ("The Library"), Euripides ("Electra," "Bacchae," "The
Cyclops," and others), Aeschylus ("Agamemnon," "Prometheus Bound," "Seven
Against Thebes," and others), Hesiod ("Theogony," "Works and Days,")
Sophocles ("Oedipus Rex," "Philoctetes," "Antigone," and others), and, of
course, the Roman poet Ovid ("Metamorphoses"). Any character who appeared
in any of these works -and some others- are now established as
mythological. Presumably, many of these poets derived their works from
much older sources and so didn't actually invent the characters,
themselves. Then we have the delightful example of Aristophanes, the
humorous poet who wrote plays such as "The Birds," "The Clouds," "The
Wasps," and "Lysistrata." His plays were intended to be comical, as
opposed to the serious and epic works produced by Homer. Koalemos
was mentioned only once by Aristophanes in his play "The Birds.": "Come,
take a chaplet, offer a libation to Koalemos (Coalemus) the god of
stupidity and take care to fight vigorously." Apart from another brief
mention in Plutach's "Lives," that is the only time Koalemos appears at
all. A few lines among the countless thousands of lines comprising the
entirety of mythological writings. Some mythographers would assert that
Aristophanes was no mythological poet at all, only a satirical one. That
statement might well be true. Yet, the characters from his plays have
become incorporated into the wider mythological community. So, even
though he was not part of the Olympian jet-set, did nothing of note, and is
recorded to have said nothing at all, somewhere up here among the boundless
cerulean blue skies lurks Koalemos, the god of stupidity.
THE SOUTHWORTH PLANETARIUM
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Julian Date: 2459061.16
2019-2020: CLXXXVI
THE DAILY ASTRONOMER
Thursday, July 30, 2020
Remote Planetarium 73: Star Questions
As we're finishing our section about the stars, we wanted to post a few
questions and answers pertaining to them. Soon (mid to late next
week), we will begin our exploration of the Milky Way Galaxy.
*If the Universe contains trillions of stars in every direction, why isn't
the night sky as bright as day?*
German astronomer F.W. Olbers (1758-1840) posed a similar question, one
that confounded astronomers and philosopher's alike. "If the infinite
Universe is static and contains an infinite number of stars, why isn't the
sky uniformly bright?" By Olbers' reasoning, every single line of sight
should intersect a star somewhere. A Universe that is infinite in age,
extent and stellar population should never produce a night sky.
Olbers' 'paradox' and JO's query sound similar, but are not exactly alike,
JO's question differs because its very phrasing contains the answer. It
also resolves Olbers' Paradox.
The resolution pertains to the Universe's age. The Universe is not
infinitely old, but, instead, as JO indicated, is about 13 billion years
old. The Universe hasn't been generating stars forever, only for billions
of years. Consequently, the cosmos hasn't had sufficient time to fill the
sky with stars. Lord Kelvin (1824-1907) proposed this age solution, which
was corroborated years later by Big Bang theorists George Lemaître and
Edwin Hubble. The dark night sky is direct observational evidence that we
live in a Universe that was born at a specific time.
Or, in other words, the Universe doesn't have enough stars to fully
illuminate our skies. While the Universe contains trillions of stars
distributed through billions of galaxies and also dispersed through
intergalactic space, the distances between us and most of those stars is
unfathomable. The light intensity diminishes with the square of the
distance. So, not every line of sight will connect with a star that we can
actually see.
Of course, if you ever have a chance to observe the night sky through
binoculars, you will see far more stars than are visible with the unaided
eye. The sky is truly alight with stars, although some of them are hidden
from our view.
*How did they determine the relationship between a Cepheid variable's
brightness and variability period?*
Like all variable stars, Cepheids exhibit a variable brightness. Over the
course of time (between 1-70 days), a Cepheid progresses through a complete
cycle from maximum brightness to minimum and then back to maximum
again.Outer layer pulsations alternately increase and decrease the star's
size and temperature, both of which affect the star's luminosity, or energy
output. As Henrietta Swan Levitt discovered, a Cepheid's variability period
relates directly to its luminosity. The longer the variability period, the
more luminous the Cepheid. Through observations of Cepheid variables,
astronomers have determined the distances to other galaxies. They compare
the Cepheid variable's apparent brightness with its intrinsic brightness.
The difference between observed and actual brightness yields the distance.
Henrietta Swan Leavitt discovered the Period-Luminosity Relation by
observing Cepheid variable stars with the Small Magellanic Cloud. This
"Cloud" is a satellite galaxy to the Milky Way at an estimated distance of
160,000 light years from Earth. Even though the SMC has an diameter of
7,000 light years, we can assume that all the stars are at more or less the
same distance from us. Similarly, we can assume that every citizen of Los
Angeles County is at the same distance from Portland, Maine.
Professor Leavitt surveyed the Cepheid variables within the SMC and noticed
that the brightest Cepheids exhibited the longest variability periods.
Through careful observations, she determined a correlation between the
Cepheid variable's brightness and variability period. These observations
served to established a relationship only. Direct distance determination of
Delta Cephei, the very first Cepheid discovered - hence, the name -
provided astronomers with that Cepheid's luminosity. This knowledge
provided them with the key to establishing the actual period luminosity
relation.
[Note: by measuring Delta Cephei's distance through parallax, they could
compare its apparent brightness and distance to determine the star's actual
brightness, or luminosity. Distance, apparent brightness and absolute
brightness are the three factors involved in the "distance modulus"
equation. The determination of two yields the value of the third.]
*Are there as many stars below our feet as exist above our head?*
[image: Stars within 100 light year radius]
This image shows the Sun and the stars within the immediate vicinity.
Produced by National Geographic, this chart illustrates that our Sun and
the other stars all "float" in the void. For convenience, the graphic
artists placed Sol in the dead center, to enable us to gauge the up/down
positions of the proximate stars.
Let's imagine that Earth were a transparent glass globe so that we could
look through the ground to observe the stars as easily as we observe them
above us. On this imaginary sphere, one finds stars in every direction.
Many of those stars we see below our feet are those stars that can never
actually see at the mid-northern latitudes, such as Pavo, the Peacock, Crux
(the Southern Cross) or Tucana, the Tucan. With Earth obscuring internal
material taken away, we can see most everything, apart, of course, from
those stars around the Sun. Of course, as we're delving in our own
imaginary Universe, we can snap the Sun off, too, if we so choose.
The Milky Way Galaxy is about 10,000 light years thick around its halo.
This thickness tapers down to about 1000 light years toward the outer
spiral arms. Our Galaxy is a barred spiral. In such galaxies, curling arms
extend away from a central bar structure. The Sun and it attendant bodies
occupy a minuscule niche within the Orion Arm about 23,000 light years from
the center. Within our neighborhood, stars are most abundant along the
spiral arms, but are also scattered "above" and "below'" the arms. It is
for this reason that we see the richest star fields within the "Milky Way"
bands and far fewer stars away from these bands. However, we still see
quite a few stars in all directions because our solar system is part of a
great swarm within this galactic region.
So, the void falls away into the infinite under our feet just as it does
above our heads. Fortunately, the planet's gravity holds us fast to its
surface. It gives us a ground that ultimately, is spinning and turning in
the boundless vacuums of the cosmos.
*How far away could we travel from the Sun while still being able to see
it with the naked eye?*
First, a little background. Actually, this answer is more of an
approximation. The Sun is by far the sky's brightest night sky object
because we are so close to it: between 91.5 - 94.5 million miles, depending
on the time of year. All the other stars are much fainter because they are
so far away. (Think about it this way: a light beam requires about 8.3
minutes to travel from the Sun to Earth. A light beam from Proxima
Centauri, the closest star to the Sun, requires about 4.2 years to reach
Earth. Proxima Centauri is about 262,000 times farther away from us than
the Sun.)
If we were to travel away from the Sun, it would become fainter. At Pluto's
distance, the Sun will still be many millions of times brighter than the
night sky's brightest star, Sirius. At the distance of Proxima Centauri,
the Sun would be about as bright as Procyon, the brightest star in Canis
Minor and the 8th brightest star in our sky. The faintest stars that most
people can see are about 185 times dimmer than Procyon. For the Sun to
appear this faint to us, we would have to be about 58 light years away from
it. Some people have keener eyesight than most of us and they can see
fainter stars. However, if we were all in a space vessel that was 58 light
years from the solar system, we could still just barely see the Sun. We'd
likely need a highly detailed star chart to locate it.
*What is the closest invisible star to us?*
The closest "invisible" star, called Barnard's Star, is only six light
years away. Barnard's Star is a low mass red dwarf. A red dwarf is a star
that is just massive enough to have ignited and sustained thermonuclear
fusion reactions in its core. A star is considered "active" if its core
active fuses lighter elements into heavier ones. A star's luminosity, or
energy output per unit time, depends on its mass. The more massive the
star, the higher the luminosity. A low luminosity star is comparatively
quite faint.
Barnard's Star is about 25 times fainter than the faintest stars visible to
the unaided eye. In fact, Barnard's Star would have to be 1.2 light years
from Earth to become as bright as the faintest naked eye stars. The closest
star system to the solar system, Alpha Centauri, is 4.2 light years
away.
We shouldn't be surprised by this answer, considering that less than ten of
the thirty closest star systems to the Sun are visible to the unaided eye.
Most stars are red dwarfs and therefore quite faint. We see only the
biggest, brightest and, on occasion, the nearest.
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