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Backyard Astronomy. Introduction to Constellations. 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.
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Backyard Astronomy Introduction to Constellations
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.
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 • 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 • Named Stars • POLARIS (Alpha UMi) • KOCAB (Beta UMi) • Pherkad (Gamma UMi) • Yildun (Delta UMi) • Pherkad Minor (11 UMi)
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 • 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 • 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 • 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 –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 • Named Stars • SHEDIR (Alpha Cas) • Caph (Beta Cas) • Ruchbah (Delta Cas) • Segin (Epsilon Cas) • Achird (Eta Cas) • Marfak (Theta Cas) • Marfak (Mu Cas)
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 • 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)
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 • 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
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.
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.
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.
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...)
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.
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.
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".)
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.
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.
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.
