University of Michigan - Department of Astronomy

updated: 04/19/2000


Finding Constellations
in the Night-time Sky
of Ann Arbor

Some man of yore
     . . . thought he good to make the stellar groups,
That by each other lying orderly, they might display their forms.

And thus the stars
     at once took names and rise familiar now.

-- 18th-century translation of Aratus, c. 3rd-century BC

Objectives

Introduction

You can see many wonderful things in the night sky, if you can find a place where it is dark and clear. Then you might be able to see the Milky Way stretching from horizon to horizon like a luminous cloud, or maybe even catch a meteorite flaming to earth out of the corner of your eye. However, we live in Ann Arbor. Here the weather is not clear very often and the lights of the city blot out all but the brightest of objects. We are left with only the bright stars, the nearest planets, and - of course - the Moon. This short guide will help you start 'looking up' at night to what we can see here. A sky chart from class or a constellation wheel will help you find the constellation shapes that are described here.

The first thing to do is to get oriented. On campus, north is approximately the direction that State Street runs. You could also picture roughly the direction of North Campus. Once you find north, you should be able to find the Big Dipper fairly easily. If you managed to find someplace dark outside of Ann Arbor, you'll have just have to scan the sky until you find the Big Dipper.


The Constellations

In tabular form here.

Circumpolar

The Big Dipper (or Ursa Major, its proper constellation name) is one of the circumpolar constellations. This means that it circles close around the north pole, and we can see it year-round. There are four other circumpolar constellations, including the Little Dipper (whose proper name is Ursa Minor), Cassiopeia, Cepheus and Draco. Because these are visible year-round in the north, they are some of our most recognizable constellations.

But anyway, you've found the Big Dipper in the north. Following the two stars at the end of the bowl in a straight line for approximately 30 degrees, or three fists held at arms' length, you end up on the north star. Polaris, the north star, is the star closest to true north. For this reason, it has long been used for navigation (and perhaps you could use it if you get lost in the Arb?). It is also the end of the handle of the Little Dipper, so now you have found a second constellation that you can see all year. Because the Little Dipper is made up of rather faint stars, Polaris might be about all you can see of it from Ann Arbor. On a clear night you should be able to make out the two stars at the end of the bowl of the dipper as well. Notice the handle of the Little Dipper bends the opposite way to the Big Dipper.

The Big and Little Dippers are linked in their proper constellation names too. They are the big and little bears, Ursa Major and Minor. One legend explains why these bears have such very long tails (the handles) compared to ordinary earth-bound bears. The legend says that when the bears were placed in the sky by Zeus, the god didn't want to get bitten or scratched by the bears' teeth or claws. In order to prevent this, he held on by the tail and swung the bears overhead to catapult them into the sky. In the process of swinging them overhead, he stretched their tails out.

Another circumpolar constellation is Cassiopeia, queen of a powerful land according to legend. In the sky Cassiopeia looks like a W or an M, depending on the time of year. The W is Cassiopeia's throne. All of her stars are bright, so this is another easy one to see. Find Cassiopeia by following the same two stars in the bowl of the Big Dipper past the north star and keep going another 30 degrees or so - that should put you near the big W.

The other two circumpolar constellations are a bit fainter, but still visible from Ann Arbor. Cepheus, the King to Cassiopeia's queen, looks like a tall skinny house or a square with a triangle on top. You can find Cepheus by imagining Cassiopeia sitting on her throne (inside the W) looking at Cepheus. The roof-top of the house sits between the north star and Cassiopeia. Draco the dragon winds between the Big and Little Dippers, generally taking up all of the remaining bright stars between those two constellations. Draco's head hangs down near Cepheus. Draco is probably the toughest circumpolar constellation to find outside, but if you can find it you could tell the 'dragon heaven' story from the movie Dragonheart.

All other constellations are far enough south that as the earth rotates, these stars rise and set. Different constellations are visible at different times of night. Since the stars rise 4 minutes earlier each night, different constellations are also visible in different seasons (at any particular time of night). The following seasons are based on what you would see outside at ten o'clock.

Winter

Winter is the season of Orion, the hunter. You can find Orion by looking for the three closely set stars in his belt a little further south than overhead. Once you have seen these a couple of times you will be able to recognize them anywhere. As well as the belt, Orion includes shoulders (the two bright stars above his belt, to the north), two feet (the two bright stars further south) and a scabbard hanging from his belt (which may be a little faint to see here). There are several legends involving Orion, many of them not so complimentary to the giant hunter. One involves Orion becoming enamored of the Pleiades (who were seven earthly women at the time, all daughters of a king). He eventually became so obsessed with them that the gods took pity on the girls and whisked them away to the sky on the back of a bull. They became the group of stars called the Pleiades and the bull became Taurus. Obviously Orion managed to follow them, and still chases them across the sky.

Orion is the key to the winter constellations, because you can find most of the rest of them using reference points on Orion. Find Orion's belt, and follow an imaginary line through it until you come to a very bright star. This star is Sirius, the dog-star. It is the brightest star in the nighttime sky. There are many stories involving Sirius. In ancient Egypt it was called the "Nile Star" or the "Star of Isis" because its annual appearance preceding sunrise on the day of the summer solstice marked the ensuing rise of the Nile River. In medieval Europe it was associated with the "dog days of summer" since it was thought that the summer heat resulted from the mixing of Sirius's light with that of the Sun. Its appearance was regarded was an evil omen. Sirius is also the nose or eye of Canis Major, the big dog. The rest of the body of the dog is closer to the horizon and fainter, but does follow a stick figure of a dog.

Another dog, Canis Minor, is not so lucky. The little dog is indeed 'little' - only two stars. The brighter one of these, Procyon, can be found by following an imaginary line through Orion's shoulders and approximately straight up from Sirius. Canis Minor and Canis Major are the two hunting dogs of Orion, following at his heels through the sky.

An imaginary line through Rigel, Orion's right foot, and up through Betelgeuse, Orion's left shoulder, points toward the brightest star in Gemini. Gemini has a kind of box-like shape, but perhaps is best recognized by its two "twin stars". Castor and Pollux appear very similar, and are separated by only 4.5 degrees. Castor and Pollux are each the head of one twin. Stick figures descend from these heads towards Orion, making up the rest of the constellation. One legend claims that one day while Castor and Pollux lived on earth, Pollux had some kind of tragic accident and was killed. Castor was so upset by his twin's death he went to visit him in Hades. There he was given a chance at immortality: he could return to the earth and be immortal, but his brother would stay dead. Castor couldn't bear the thought of life while his brother Pollux spend eternity in Hades, so he asked if instead they couldn't share the immortality -- one would live on the earth for six months while the other took his turn being dead, then they would switch. The gods were so touched by his loyalty to his brother, they took them both and turned them into stars so they could be together forever.

Taurus the bull, who carries the Pleiades on his back, is a large constellation in the winter sky. Follow Orion's belt in roughly a straight line in the opposite direction of Sirius (so follow it to the west), and you will find yourself near a big V in the sky. This V is Taurus's face. The rest of Taurus is made up of a body somewhere in the stars nearby -- the Pleiades ride on his back, and you can sort of see two front legs. If you follow the two branches of the V upward for about four times their length, you find the tip of Taurus's horns. The bright star at the end of one horn is called Capella, and is shared with the constellation Auriga.

Auriga the goatherder is perhaps easiest to find by following Taurus's horns to Capella. Then Capella is one arm of a stick figure which holds three goats under the other arm. The three goats look like a tiny triangle of stars. Auriga is also called the charioteer, and you can make the same stars into something that looks like a chariot driver sitting down, holding the reins. Several open star clusters are located in Auriga, each containing about one hundred stars. If you find a dark location, these would appear as fuzzy knots in binoculars.

Spring

Part of the key to spring is the Big Dipper, which you've already found. The rest of the key is a rhyme, "Arc to Arcturus, Speed on to Spica". This means follow arc of the handle of the Big Dipper and keep going until you come to a very bright star. This is Arcturus, the bottom of a kite or ice cream cone shape that makes the constellation Bootes. So now you need to speed on to Spice -- keep following the same arc past Arcturus until you come to another bright star. This is Spica, the brightest star in the constellation Virgo the virgin.You can form a reclining woman out of the stars in Virgo, but it is easier to form an upside pi symbol, p. Spica is at the southeast end of the top line in the pi.

There is a legend about Ursa Major which ties in with the spring constellation, Bootes. Before Ursa Major came to be a constellation, she used to be a woman called Callisto. Callisto was a one of Artemis's virgin huntresses. Zeus became infatuated with her and mated with her, producing a son. As a result, Artemis threw her out of her hunting group because obviously she was no longer a virgin. Then Hera, Zeus's wife and a very jealous woman, was able to turn Callisto into a bear for revenge. Callisto did not have an easy time as a bear, being hunted all the time. Her son, Arcas, came upon her one day while he was hunting and didn't recognize that she was his mother. Luckily for the two of them, Zeus saw what was about to happen and averted the matricide by placing Callisto and Arcas in the sky. Callisto became the great bear, Ursa Major, and Arcas became Bootes the herdsman.

Virgo was known as the Wheat-bearing Maiden, Maiden of the Harvest and generally as a symbol of the Earth-mother or of the harvest. As such, she was identified to the Greeks as Persephone, daughter of Demeter. She was also associated with the goddess of Justice, who ruled over the earth during the Golden Age when the gods lived on earth. When mortals took over the earth and disregarded law and order, she fled to the sky with her scales of justice (which became the constellation Libra). She sits there laughing at us today.

Back over next to Bootes is the constellation Corona Borealis, the northern crown. It looks like a backwards C right next to the ice cream cone of Bootes. This is a rather pretty constellation to look at.

Summer

Each season so far has had a key to help you find the constellations, and summer is no exception. The key to summer is in fact an 'asterism', that is, a group of stars that are not a constellation but have a common name. The key to summer is the Summer Triangle, made up of the stars Vega, Deneb, and Altair. This is easily visible overhead during the summer. The three stars are the brightest in the sky and make a really big triangle. The next step is figuring out which star is which.

It's easiest to start with finding Deneb. Deneb is the brightest star in the constellation Cygnus the swan. Each of the three bright stars of the summer triangle are near other stars, but Cygnus's stars make a big cross in the sky. For this reason it is sometimes called the Northern Cross. The longest part of the cross points into the center of the summer triangle, this part represents the swan's long neck. Deneb is at the crux of the cross. The two wings of the swan spread out to each side, and in the opposite direction to the neck is a very short tail. If you can see the Milky Way, you will see that Cygnus looks like it is flying along the stream of the Milky Way.

After finding Cygnus, the bright star in the summer triangle that is further north or at about the same distance north is Vega. Vega is in the constellation Lyra the lyre. Lyra is fairly faint except for Vega, but you should be able to make out an arc above Vega. This is where the strings for the lyre would be attached. Lyra represents the instrument given to Orpheus by Apollo. Orpheus was the most talented musician of his age, his music would make the trees weep. The most famous use of his talent was to charm Hades into allowing his wife to return to the land of the living. Unfortunately, Orpheus didn't follow Hades instructions not to look back at her as she followed him out of the underworld, and so he lost her forever.

Now there is only one more star in the summer triangle, Altair. Altair is the head of Aquila the eagle. Aquila's body swoops out in the somewhat the same direction as Cygnus's neck, and you can pick two wings out of the nearby stars. Ancient Greeks saw Aquila as the eagle which tore at Prometheus's liver as punishment for bringing fire to humans. If you look at it in the sky, it appears to be swooping on a small nearby constellation that looks like a mouse with a long tail or a dolphin jumping out of the water. That constellation is Delphinius.

Following a line from Deneb through Altair and all the way to almost the southern horizon brings you to Sagittarius, the archer. You can collect these stars into an archer, but it is much more common to make them into a teapot. Perhaps it should be Sagittarius the teapot. The lid of the teapot points to the north. The body of the pot even includes a spout and handle. Sagittarius is believed to be in the direction of the center of our galaxy.

Next to Sagittarius you can find a large "J" shape. This is Scorpio the scorpion. The J is his body, the curve of the J on the southern horizon is his stinger held up in defense. Some legends of Orion say this is the scorpion that killed him and so was placed in the summer constellations so that it could never hurt him again. One of the reddest stars in the sky, Antares, is located in the J of Scorpio.

Fall

The autumn constellations are all part of one big legend, the story that was made into Clash of the Titans. Cassiopeia, the queen you found earlier, was a very vain and proud woman. She boasted that she was the most beautiful woman in all the world, more beautiful than even the sea nymphs. Poseidon, the father of the sea nymphs, was more than a little upset by these boasts. He sent a sea monster to plague her land by eating her subjects and preventing them from going to sea to fish. The kingdom was in bad shape, so Cassiopeia and her husband, King Cepheus, (who you also found earlier), went to see the oracle at Delphi to find a solution to the sea monster problem. The oracle said the only solution was to sacrifice their daughter Andromeda. They were to chain her to the rocks on the beach and let the monster eat her. Being very concerned about their country, they decided to do as the oracle said.

Find Andromeda by locating Cassiopeia, then following a line straight out from the center of the W, away from the north star. You should see a line of three bright stars. The one furthest from Cassiopeia is Andromeda's head, the middle one is her bottom, and the last is her foot. Probably too faint to see from Ann Arbor is her kneecape, which is the Andromeda Galaxy and not actually a star. She also is waving about two arms, which you might not see from Ann Arbor either. She is sitting, chained onto the rocks.

Cassiopeia and Cepheus had already chained Andromeda up on the rocks and were waiting for the sea monster, when Perseus the hero showed up. Perseus on his way home from his quest where he had killed the Medusa who turned men into stone. As such, Pegasus the flying horse and the decapitated head of the Medusa were with him.

Find Perseus by following the zig of the W from the center to the side nearest the Big Dipper. He is to the east of Andromeda. Perseus looks like a Greek sign lambda, or even a coat hanger to modern folks. In truth, he is up there running towards Andromeda to save her. His head is the top of the lambda, pointed towards Cassiopeia, and his legs are the two branches. He even has two arms that look like he's running hard.

Find Pegasus by following the other zig of the W out towards the west of Andromeda. You should see a big square made up of bright stars, one of which is Andromeda's head. This is called the Great Square of Pegasus (another asterism). Pegasus is made up of three of the stars of the square, which are his triangular wings, and long legs which hang below his wings. His head also hangs down by his legs, as if he were bucking and fighting with something (the sea monster?).

Perseus and Pegasus save the Princess Andromeda by turning the sea monster to stone with the Medusa's head. Perseus then asked Andromeda to marry him, but her parents Cassiopeia and Cepheus refused to allow it. Perseus promptly turned them into stone and married her anyway.


There are many more constellations in the sky. I have only talked about the brightest and most well-known ones. Also, there are many legends about the constellations, including legends from other civilizations. Some, like an American Indian legend of Orion point out clever things about the sky. There Orion was a good man, a fine member of the tribe. He lived a long life, and when he became old, he didn't want to be a burden on the tribe by requiring too much care and assistance. So one day, he got his affairs in order and just left the camp. He kept walking and walking, and the ground started to slope up underneath his feet. He kept walking, until eventually he got so high he was in the sky. He became the constellation Orion. Orion is not visible in the summer months, so the members of his tribe believed he was 'carrying' the sun during that time, giving them good light and warm weather. When his son came to join him in the sky, his son was not quite so careful about his duties, being a bit lazy. His son was a summer constellation -- so he carried the sun in the winter, and since he was lazy, he carried the sun low in the sky, leaving the earth cold and dark. This legend explains the difference between summer and winter, and also points out the reason winter constellations aren't visible in the summer is because they are in the direction of the sun.

For visual pictures of the constellations, a "constellation wheel" (which you can set to your day/time to see what is actually in the sky) is an excellent tool, and skycharts can be very helpful. There are also some places on the web that will help you visualize constellations and see what is visible to you in your location.