Transcript document

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.
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.
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.
Circumpolar Constellations
“Circum” means around (i.e.
circumnavigate, circumference). Polar
refers to the North Pole. Therefore,
circumpolar constellations circle Polaris.
This makes the 5 circumpolar
constellations visible throughout the
entire year. Let’s look at each!
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
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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 Minor
Ursa Minor
Named Stars
POLARIS (Alpha UMi)
KOCAB (Beta UMi)
Pherkad (Gamma UMi)
Yildun (Delta UMi)
Pherkad Minor (11 UMi)
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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
The Big Dipper
Ursa Major
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Named Stars
DUBHE (Alpha UMa)
MERAK (Beta UMa)
PHAD (Gamma UMa)
MEGREZ (Delta UMa)
ALIOTH (Epsilon UMa)
MIZAR (Zeta UMa)
ALKAID (Eta UMa)
Talitha (Iota UMa)
Tania Borealis (Lambda UMa)
Tania Australis (Mu UMa)
Alula Borealis (Nu UMa)
Alula Australis (Xi UMa)
Muscida (Omicron UMa)
Muscida (Pi 1 UMa)
Muscida (Pi 2 UMa)
ALCOR
ORION
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Perhaps second only to the Big Dipper in Ursa Major, the constellation of
Orion is one of the most recognizable patterns of stars in the northern sky.
Orion, the hunter, stands by the river Eridanus and is accompanied by his
faithful dogs, Canis Major and Canis Minor. Together they hunt various
celestial animals, including Lepus, the rabbit, and Taurus, the bull.
According to Greek mythology, Orion was in love with Merope, one of the
Seven Sisters who form the Pleiades, but Merope would have nothing to do
with him. Orion's tragic life ended when he stepped on Scorpius, the
scorpion. The gods felt sorry for him, so they put him and his dogs in the
sky as constellations. They also put all of the animals he hunted up there
near him. Scorpius, however, was placed on the opposite side of the sky so
Orion would never be hurt by it again.
From the northern hemisphere, the three bright stars (Alnitak, Alnilam and
Mintaka) in a straight line that form Orion's Belt are easily visible on the
southern horizon in winter evenings. The bright star that forms Orion's left
shoulder is Betelgeuse. The name of this star means "The Armpit of the
Central One" in Arabic, which shows that like many other constellations,
Orion was recognized across many cultures.
ORION
ORION
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Named Stars
BETELGEUSE (Alpha Ori)
RIGEL (Beta Ori)
BELLATRIX (Gamma Ori)
MINTAKA (Delta Ori)
ALNILAM (Epsilon Ori)
ALNITAK (Zeta Ori)
Nair al Saif (Iota Ori)
SAIPH (Kappa Ori)
Meissa (Lambda Ori)
Tabit (Pi 3 Ori)
Tabit (Pi 2 Ori)
Tabit (Pi 4 Ori)
Tabit (Pi 1 Ori)
Thabit (Upsilon Ori)
Cassiopeia
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Queen of Ethiopia or Andromeda's Mother
Cassiopeia was the wife of King Cepheus. She was very
pretty, and would often boast that she and her daughter
were more beautiful than the sea nymphs, the Nereids.
They complained to Poseidon, who unleashed a monster
onto Cepheus' land. In order to save their country, the
king and queen sacrificed their daughter, Andromeda.
Just before the monster, named Cetus, ate the princess,
Perseus saved her. All five figures are represented in the
sky as constellations.
Cassiopeia has a very distinct shape. She looks like a "W"
or "M" in the sky, depending on where she is. Some
legends say that Cassiopeia was chained into the sky and
sometimes hangs upside-down to remind others not to be
so boastful.
Cassiopeia
Cassiopeia
Named Stars
SHEDIR (Alpha Cas)
Caph (Beta Cas)
Ruchbah (Delta Cas)
Segin (Epsilon Cas)
Achird (Eta Cas)
Marfak (Theta Cas)
Marfak (Mu Cas)
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Cepheus :
King of Ethiopia or Andromeda's Father
Cepheus is one of the oldest constellations in the
night sky. This house-shaped constellation is named
after an ancient king of a land called Ethiopia
(different from the current country, Ethiopia). He was
married to the beautiful Cassiopeia and had a
daughter, Andromeda.
In Greek mythology, Cassiopeia boasted that she and
her daughter were more beautiful than the Nereids.
They complained to the sea god Poseidon, who sent a
monster to destroy Cepheus' land. The king and
queen offered their daughter to the monster, but she
was saved by Perseus.
Cepheus
Cepheus
Named Stars
ALDERAMIN (Alpha Cep)
Alfirk (Beta Cep)
Alrai (Gamma Cep)
Herschel's "Garnet Star" (Mu Cep)
Alkurhah (Xi Cep)
Al Kalb al Rai (Rho 2 Cep)
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Draco
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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
Draco
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Named Stars
THUBAN (Alpha Dra)
Rastaban (Beta Dra)
ETAMIN (Gamma Dra)
Nodus Secundus (Delta Dra)
Tyl (Epsilon Dra)
Aldhibah (Zeta Dra)
Ed Asich (Iota Dra)
Gianfar (Lambda Dra)
Arrakis (Mu Dra)
Kuma (Nu 2 Dra)
Grumium (Xi Dra)
Alsafi (Sigma Dra)
Dsiban (Psi 1 Dra)
About 4000 years ago, the star Thuban was the North Star. Since
then, precession of the Earth's axis has changed where the North
Pole points, so the North Star is now Polaris. In another 10,000
years or so, the North Star will be Vega.
Signs of the Zodiac
Ecliptic Constellations
As the Sun traverses the ecliptic path, it
appears to move against a band of 12 ancient
constellations called the Zodiac
Ecliptic
Constellations
Ecliptic
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.
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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
Gemini The Twins
Gemini, the Twins, are really only halfbrothers. 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...)
Gemini
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