Transcript Introduction to Constellations

Introduction to Constellations
Backyard Astronomy
The Night Sky
People have watched the night skies for
millions of years. Some just out of
curiosity. Some out of boredom. Some
looking for portents, either good or bad.
However, the one thing that they all saw
was that there was a pattern in the way
the stars revolved around the heavens.
The Night Sky
You need only to look up for a few hours to
begin to see these same patterns yourself.
Like the Sun, stars rise in the east and set
later in the west. Planets follow this same
pattern unless they are in a retrograde
period, though these periods are not
especially common.
What You Need for Stargazing
You don’t really need anything, but some
things are handy, like…
Complete darkness-Don’t laugh, it’s not
that easy to find. Rural area are slowly
being urbanized, bringing their lights with
them. Light pollution is a real problem.
What You Need: Darkness
Darkness means keeping up with the
phases of the moon, too. When the moon
is waxing past half full, it’s quite hard to
see.
What You Need: Star Map/ Planesphere
It is handy to have a star map to help get
you oriented.
Star Maps are also called planespheres.
You can find them in hobby stores for a
couple of bucks.
Finding Polaris and Why
Polaris (or the North Star) is where you
want to start. Because Polaris is aligned
with the Earth’s axis of rotation, it remains
fixed, with all the other planets and stars
appearing to move around it. It is the one
star that remains fixed at all times.
Getting Oriented or Where the Heck is
North?
Yea, you have to find north. It’s where Polaris
(or North Star) is. You’ll need a compass or
major highway to orient yourself. Highway 17 is
good because it runs due north and south.
You can make a compass with a needle, magnet
and a cup of water. Just rub the needle across a
magnet (see your refrigerator) or leave it attached
overnight. Then rub the needle across your nose
and place it in the cup very gently. It will float. It
will turn north.
Figuring the Angle
Once you’ve decided where north is (right
ascension), face in that direction. Next you have
to figure declination (up and down). Extend your
arm and make a fist. Put the bottom of your fist
on the horizon. The top of your fist is about 80
higher. Place your other fist on top of your first.
You’ve now measured 160 up from the horizon.
Polaris is located between 250 and 300 above the
horizon. Polaris is faint, so look carefully!
Another Way to Find Polaris
If all that compass making and angle junk
is just too complicated, there is another
way to find Polaris. Find the Big Dipper
(part of a constellation). Most people
recognize this asterism. The two stars that
form the front of the cup of the dipper
define a line pointing to Polaris.
The Big Dipper
The Stars Circling Polaris
Now That You’re Oriented, It’s Time
to Explore.
You’re pointed in the right direction, but what now.
Stars and constellations move constantly and
seasonally. What am I looking for? What you need is a
star map.
A Few Constellations...
14
Ursa Minor
Once you’ve located Polaris, you’re ready
to identify your first constellation. Polaris
is the last star located in the handle of the
asterism, the Little Dipper. The name of
the constellation that contains the Little
Dipper is Ursa Minor or Little Bear.
Ursa Minor


Ursa Minor, also called the Little Dipper, is a
circumpolar constellation. This means it never
sets in the northern sky. The true figure
represented by the stars is the Little Bear.
There are several mythological stories behind
these famous constellations. In Greek myth, Zeus
was having an affair with the lovely Callisto.
When his wife, Hera, found out she changed
Callisto into a bear. Zeus put the bear in the sky
along with the Little Bear, which is Callisto's son,
Arcas.
Ursa Minor
Ursa Major
Ursa Major is probably the most famous constellation, with
the exception of Orion. Also known as the Great Bear, it has
a companion called Ursa Minor, or Little Bear. Everyone
living in the Northern Hemisphere has probably spotted the
easily recognized portion of this huge constellation. The body
and tail of the bear make up what is known as the Big
Dipper.
Several different cultures saw a big bear in the sky. The
ancient Greeks had a few different stories to explain how the
animal ended up there. In one story, Hera discovered Zeus
was having an affair with Callisto and turned her into a bear.
Zeus put her in the sky along with her son, Arcas, who
became the Little Bear.
Ursa Major
Draco


Draco the dragon, is only present in the Northern
Hemisphere, so those living in the Southern Hemisphere will
never see this long constellation.
The easiest way to spot Draco is by finding his head. It
consists of four stars in a trapezoid, burning brightly just
north of Hercules. From there, the tail slithers through the
sky, eventually ending between the Big and Little Dippers. It
can be difficult to trace Draco in the night sky. From the
head, follow the body north towards Cepheus. It suddenly
shifts south and west, ending up between the two dippers.
The end of the constellation is held by Thuban, which was
the pole star over 4,000 years ago.
Draco
Orion’s Belt
22
Cassiopeia

Cassiopeia was the beautiful wife of Cepheus, king of
Ethiopia, and the mother of Andromeda. She is most famous
in connection with the myth of her daughter, Andromeda. The
queen made the mistake of bragging she was more lovely
than the Nereids, or even than Juno herself. The goddesses
were, needless to say, rather insulted, and went to Neptune,
god of the sea, to complain. Neptune promptly sent a sea
monster (possibly Cetus?) to ravage the coast. The king and
queen were ordered to sacrifice their daughter to appease
Neptune's wrath, and would have done so had Perseus not
arrived to kill the monster in the nick of time. As a reward, the
hero was wedded to the lovely Andromeda.
23
Cassiopeia
24
Cygnus

Cygnus is a constellation in the northern sky. Its name means
“the swan” in Latin, and it is most frequently associated with
the myth of Zeus and Leda. The Swan constellation is easy
to find in the sky as it features a well-known asterism known
as the Northern Cross.

Cygnus constellation is associated with several myths, most
frequently the one of the Spartan Queen Leda, who gave
birth to two sets of twins, the immortal Pollux and Helen and
mortal Castor and Clytemnestra, after being seduced by the
god Zeus, who had transformed himself into a swan. The
immortal children were fathered by the god and the mortal
ones by Leda’s husband, King Tyndareus. Castor and Pollux
are represented by the zodiac constellation Gemini.
25
Cygnus
26
Signs of the Zodiac
Common Constellations
Aquarius: The Water Bearer
In Greek mythology Aquarius was Ganymede, "cup-bearer to
the gods". Alpha Aquarii ("Sadalmelik") and beta Aquarii
("Sadalsuud") are twin supergiants with nearly identical
names. The names mean, respectively, "The Lucky One of
the King" and "The Luckiest of the Lucky". Gamma Aquarii
shares in the good fortune: "Sadachbia": "The Lucky Star of
Hidden Things" Incidentally, if the "Age of Aquarius" was
celebrated in the 1960s, the real event is still some 600
years off: at that time Aquarius will contain the vernal
equinox, marking the return of the Sun into the northern
celestial hemisphere.
Aquarius: The Water Bearer
Aries: the Ram
Aries, "The Ram", is an ancient constellation which was of
considerable importance since the sun passed through it at
the vernal equinox.

This point has now moved into Pisces, but the vernal equinox is
still known as the First Point of Aries. In another six hundred
years the point will have moved into Aquarius.
The Ram in question may have been the one whose golden
fleece was the object of Jason's quest.
There is some reason to believe that the Greeks just took
over a much older horned animal at this time of the year; the
horn being a symbol for fecundity, renewal, and so on. As
the Sun came into this constellation, at the vernal equinox,
the year itself was being renewed.
Aries: the Ram
Cancer The Crab
The name comes from the Latin; cancer
means crab. The crab in question is the
one sent by Hydra to attack Heracles. It
was only a bit part, but one which secured
its immortality.
Cancer
Capricornus the Sea-Goat
The Sea Goat or Goat-Fish, as a creature with
the head and body of a goat and the tail of a fish,
may well have originated from Assyro-Babylonian
depictions of their god of wisdom Oannes, who
was half-man, half-fish.
34
Capricornus
Gemini The Twins
Gemini, the Twins, are really only half-brothers.
They share the same mother (Leda) but have
different fathers. Castor's father was a king of
Sparta, Tyndareus - who would be chased from
his throne but later rescued by Heracles (who
nevertheless wound up killing him). The father of
Pollux was none other than Zeus, or Jupiter. Zeus
visited Leda on her wedding night in the guise of
a swan. Thus the twins would be born. (In fact
two twins came from this double union, but let's
not complicate the matter even more...)
37
Leo: The Lion
The first on the list of Heracles' labors was the
task of killing the Nemean Lion, a giant beast that
roamed the hills and the streets of the
Peloponnesian villages, devouring whomever it
met. The animal's skin was impervious to iron,
bronze, and stone. Heracles' arrows harmlessly
bounced off the lion; his sword bent in two; his
wooden club smashed to pieces. So Heracles
wrestled with the beast, finally choking it to death.
He then wrapped the lion's pelt about him; it
would protect him from the next labor: killing the
poisonous Hydra.
Leo
Libra: The Scales
Libra means "The Scales" or "Balance", so named because
when the zodiac was still in its infancy, some four thousand
years ago, the sun passed through this constellation at the
autumnal equinox (21 September). At the two equinoxes
(Spring and Autumn) the hours of daylight and darkness are
equal. As a symbol for equality, the constellation came to
represent Justice in several middle Eastern cultures.
However, the Greeks had a different perspective; at one time
Scorpius, which lies just to the east, was much larger, and
the stars that make up Libra were then known as the Claws
of the Scorpion.
Libra
Pisces: The Fish
Pisces is an ancient constellation derived, some say,
from the story of the terrible Greek god Typhon.
(This is not the Chinese word for "big wind", which - in
English - is of course spelled "typhoon". The French,
however, spell this word "typhon", which adds to the
confusion. It is possible that the Chinese borrowed
the word from the Greek. The modern Greek
equivalent is spelled "tau upsilon phi omega nu" and
means "cyclone".)
Pisces
Sagittarius
It was the Romans who named the constellation
Sagittarius ("sagitta" is Latin for `arrow'), although
several stars carry Arabic names which identify
just which portion of the constellation they
represent. Sagittarius has a muddled history. In
ancient times the asterism of three bright stars in
a curved line was seen as a bow to some, leading
both Greek and Roman writers to confuse the
constellation with Centaurus.
Sagittarius
Scorpius: The Scorpion
As mentioned regarding Orion, Gaia may have
sent the scorpion to kill the mighty hunter, as he
had vowed to rid the earth of all wild animals. Or
Apollo might have told Gaia of Orion's boast,
fearful that Orion had designs on Apollo's sister
Artemis. In any case it was Gaia who sent the
scorpion to kill Orion. Later the animal would
chase Orion across the heavens, but it could
never catch him, for the scorpion was so placed
that it would rise in the east only after Orion had
safely disappeared over the western horizon.
Scorpius
Taurus: The Bull
Is Taurus attacking Orion, the Hunter, or
are the Horns of the Bull the real story?
The horn was a symbol of fertility and
bountiful riches in many cultures for
thousands of years, and it is probably the
case here, for the constellation would have
announced the Vernal Equinox at around
4000 BC.
Taurus
Virgo: The Virgin
Virgo is the second largest constellation (after
Hydra). As a member of the Zodiac, Virgo has a
number of ancient myths and tales. The Sun
passes through Virgo in mid-September, and is
therefore the constellation that announces the
harvest. Virgo is often represented as a "maiden"
(as its name indicates). In antiquity, she may
have been Isis, the Egyptian protectress of the
living and the dead and the principal mother
goddess.
Virgo