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This sky map depicts the many sea-oriented constellations visible during autumn in the northern hemisphere in 2010. Credit: Starry Night [Full Story |
The traditional
constellations of autumn in the Northern Hemisphere have returned to the
evening sky and bring with them a rich body of lore and mythology ? though
their stars are rather faint.
Several of these
constellations are dwelling in the celestial "sea" ?
that is, they are of a watery nature.
These constellations include
Capricornus, the sea goat; Aquarius, the water
carrier; Pisces, the fishes; Piscis Austrinus, the southern fish; Cetus,
the sea monster; and Eridanus, the river. They are
appearing this week in the southern part of the evening sky at around 8 p.m.
local time in northern latitudes.
This
sky map shows the constellations of the southern sky in the Northern
Hemisphere this week.
The first three
constellations mentioned here form part of the zodiac;w all members of this group have been associated
with the rainy season of ancient Mideast lands.
There is also a
mythological connection between these star pictures and an ancient great flood
in the Tigris-Euphrates basin, which has sometimes been linked to the Deluge in
Genesis. Here's a tour of these water-themed constellations in the night sky:
Grotesque sea goat
Probably because the ancients knew very little about
marine life, it is not surprising that they populated the deep with every
manner of monster, including what we now call mermaids. Capricornus, the sea goat, now leaning down in the
southwest sky, is one of those odd land-sea animal hybrids the ancients were
wont to create.
It traces back to the Mesopotamian period. According to
folklore, there were some sea nymphs and goddesses playing in a field one day
when the mischievous god, Pan, saw them and joined in the fun. In order
to amuse them, he transformed himself into a goat and leaped into the
river. Instantly, the part of his body that was submerged in the water
was turned into a fish while the part out of the water remained a goat.
Zeus, who just happened to be passing by, saw Pan?s feat
and was so amused that he decreed the perpetuation of this grotesque figure in
our night sky. Although Capricornus is a goat, in the
sky it looks more like a roughly triangular figure which may suggest an
inverted cocked hat, perhaps a bird flying toward you, or even a boat.
Once, I pointed it out to a friend of mine who remarked
that (in keeping with the watery aspect) it looked "like the south end of
a bikini."
Watery tale
The rich mythology of Aquarius, the water carrier, which
hovers above and to the left of Capricornus, is very
ancient, tracing back to the earliest civilizations in the Tigris and Euphrates
valleys.
In fact, on some of their cylinder seals they pictured
these rivers as pouring out from Aquarius? water jar. The ancient Egyptians had
an equally picturesque image of this constellation that they associated with
the Nile?s
annual flooding, which, far from being disastrous, added a new layer each
year to the valley?s fertile soil.
The Egyptians believed the flooding was caused by
Aquarius dipping his water jar into the river to refill it. Quite a number of
Aquarius' stars have proper names. The names Sadalmelik,
Sadalsuud[s1] , Sadachbia, and Albali all
indicate in Arabic that these are "lucky" stars astrologically.
"Skat" means the lower foot in Arabic,
while "ancha" comes from Medieval Latin and
refers to the upper thigh or hip.
One fish, two fish
Were it not one of the 12
zodiacal signs, Pisces the fishes would not be deemed important at all.
Astronomers measure star
brightness in terms of magnitude ? the smaller the number (close to or less
than one), the brighter the object. None of the stars in Pisces shine brighter
than fourth magnitude ? though brilliant Jupiter currently resides here ? but
the constellation does display a striking, though not bright, pattern now high
in the southern sky.
It also has some historical
affinities, including one related to Christmas.
To the early Israelites,
Pisces was a sacred part of the sky. Planetary gatherings or other occurrences
of astrological significance were regarded as harbingers of important events if
they happened there.
For example, a favorite explanation
of the Star of Bethlehem is a planetary grouping involving Mars, Jupiter
and Saturn that took place in Pisces in 6 B.C.
The main legend to account
for the Fishes is that Cupid and Venus ? the god and goddess of love ? escape
the monster Typhon by jumping into a river and
assuming a piscine form.
Long-necked bird and a southern fish
In addition to the six groupings I mentioned earlier, we
might also include the constellation of Grus, the
Crane, among the watery constellations, for this wading bird often inhabits
swampy and marshy terrain.
It currently lies low near the southwest horizon. With
its two second-magnitude stars marking the bottom of a distinctive inverted
Y-shaped pattern, and with third-magnitude Gamma at the top, Grus is actually a prominent fall constellation for viewers
in the tropics and the Southern Hemisphere.
Directly above Grus is Piscis Austrinus, the southern
fish, which has the only first- magnitude star ? Fomalhaut
? in this whole collection of watery constellations.
Aside from Jupiter ? which this year happens to be
glowing brilliantly nearby in Pisces ? Fomalhaut
usually appears as a solitary star in a very dull and unexciting region of the
sky.
Indeed, Fomalhaut is the only
"true" first magnitude star of autumn. It's a white star, only about
twice as large as the sun and about 14 times as bright. It appears prominent to
us because it is only 25 light-years away.
Godzilla-fish?
East of Aquarius and south of Pisces is Cetus, a sea monster who in mythology was sent by the god
Neptune to devour the princess Andromeda.
This constellation is often
called the Whale, but in the allegorical pictures found in many of the old
star atlases it usually appears very un-whale-like (almost like Godzilla with a
fish tail!).
However, today we identify the scientific name for the
whale order is Cetacea, and the study of whales is
known as Cetacean Zoology; hence the name Cetus
identifies this constellation as a whale.
Lazy celestial river
Lastly, now coming into view low in the southeast is a
large, albeit faint and shapeless constellation known as the Celestial River, Eridanus.
It starts near the brilliant bluish-white star Rigel in Orion then flows southwestward just like a river
would: a winding stream of dim stars whose meanderings wind all the way down to
below the southern horizon. Unfortunately, stargazers in much of the United
States never get to see the very end of the river, for it ends in a blaze of
splendor.
The bluish star Achernar glows
at the end of the river, ninth-brightest star in the sky, yet so far south that
only those who live near and along the Gulf Coast (Florida, New Orleans, south
Texas), get a glimpse of it, poking a short distance above the horizon.
Also in Eridanus is
Epsilon Eridani, the third-nearest star visible to
the unaided eye.
Located at a distance of just 10.8 light years from
Earth, Epsilon has about one-third of the luminosity of our sun and is about 90
percent as large. Thus, here is a star that is reasonably comparable to our own
sun.
- Welcome
to Astronomy: Getting Started
- Telescopes
For Beginners
- Telescopes
Up! A Guide to the Night Sky's New Stargazing Season
Joe Rao serves as an
instructor and guest lecturer at New York's Hayden Planetarium. He writes about
astronomy for The New York Times and other publications, and he is also an
on-camera meteorologist for News 12 Westchester, New York.

