Ursa Major

Description

Ursa Major, the Greater Bear is the third largest constellation in the sky. What is more familiar however, are the seven stars which make up the rump and tail of this animal. We know them as the Big Dipper, in the United Kingdom, they are known as the Plough.

Many people mistakenly think that the Big Dipper is a constellation but it isn't, it is something called an asterism. An asterism is a small easily recognizable formation of stars that is usually part of a larger constellation. In this case, the Big Dipper is part of the constellation Ursa Major.

Another thing this constellation is known for is the "pointer stars." These are the two outside stars in the bowl of the dipper. A line drawn through them points to the north star.

Above 40 ° N the Big Dipper is visible all night long throughout the year. Portions of it are visible at certain times of the year all the way down to mid-latitudes in the Southern Hemisphere.

Mythology

One Greek myth tells that the nymph Callisto, a servant of the hunter Artemis was made to bear a child by Zeus. Artemis banished Callisto for impurity. Artemis gave birth to the child named Arcas. This made Zeus' wife Hera very jealous and in revenge, Hera turned Callisto into a bear which ran awy into the forest. Arcas grew up to become a hunter. One day while he was hunting, the bear Callisto heard Arcas' voice and rushed to greet her son. Arcas, not knowing the bear was his mother was about to kill her when Zeus intervened and sent both mother and son into the sky as the Greater and Lesser Bears. The way Zeus got the bears into the sky explains why their tails are so long, apparently Zeus grabbed them by their tails and swung them around over his head and finally flung them into the sky, and that is why these two bears have long tails!

Mongolia

One day when the Earth was very young, a father sent his seven sons into the forest to learn how to read the winds. They entered the woods and silently walked about while listening to every sound of the wind. When night fell, the sons set up a camp and gazed up at the brilliant stars above.

During the night, the eldest brother was awakened by a strange sound. The wind was singing. He could not understand the words but as he looked to the stars, he saw a bright flickering in the Pleiades. This light seemed to be beckoning to him and it flickered in rhythm with the wind song.

The young man immediately awoke his brothers and told them to listen to the song and help him understand what the wind was saying. The brothers joined hands and began to dance. The wind song became stronger and the brother's dance became more intense.

Suddenly the brothers began to rise toward the flickering star who was the youngest of the seven sisters of the Pleiades. She had fallen in love with the youngest brother Mizar. The brothers remained in the sky as the stars we know as the Big Dipper and if you look very closely, you can see Mizar and his love, for she had left her other sisters and joined him. That is why you only now see six stars in the Pleiades.

Native American - Blackfoot

In a camp there once lived a family of the father, mother, seven brothers and two sisters. The brothers and sisters were all grown up except for one brother and one sister, who were small children. One day, the six older brothers went on a long hunting trip. While they were away, the eldest sister fell in love with a bear. The girl's father was very unhappy and with the help from other men in the tribe, they chased and slew the bear. Then, the girl herself changed into a bear and to avenge her husband's death she attacked her parents and the other tribal members. She killed everyone but her youngest brother and sister who had hidden in their wigwam. The little brother possessed magic and was able to make it so their sister could not enter their home. The bear-woman however vowed to get them.

The two young children, the boy Okinai and the girl, Sinopa were horrified at what their sister had done and they knew they had to be very careful lest she catch them. One day, little Sinopa snuck down to the river to fetch some water when she met up with her six older brothers returning from their hunt. She told them everything that had happened and they assured her they knew of a way for them all to escape. They collected up a large number of prickly pears and told Sinopa to go home and scatter the pears all around the wigwam, leaving only a very narrow path along which she could find her way out. Late that night, Sinopa and Okinai crept out of the tent following the tiny path until they reached the spot where their older brothers waited for them.

But the bear-woman had heard them go and she rushed after them and suddenly became caught amongst the prickly pears. Bear-woman howled with pain and anger but quickly transformed herself into a bear so that she could run right through the prickly pears after her siblings.

Little Okanai saw the bear coming and shot an arrow which immediately put them all as far ahead of their sister as the arrow had flown. But still the bear was gaining on them. Then Okanai waved a feather and at once, thick, tangled bushes sprang up behind them, but the bear's magic cleared a path through them.

Finally, Okanai waved his hand and a huge tree shot up from the dirt beside them. The eight terrified people scrambled quickly up into the branches but they soon found they were not safe yet! The bear climbed the tree herself and quickly dragged four of her victims down when Okanai called on his very strongest magic! One by one, Okanai shot eight arrows into the sky and with each shot, one of the children soared up into the sky. First was little Sinopa, then the six older brothers and finally Okanai himself.

As they reached the sky, they each turned into a sky and there they are today as the group of stars we call the Big Dipper. The four stars which make up the bowl of the dipper are the four that the bear-woman had pulled from the tree. The three stars in the handle are those who were still hanging in the branches and the tiny companion star to Mizar is little Sinopa huddling close to one of her brothers!

Chinese

A Chinese legend tells the story of the four stars which make up the bowl of the Big Dipper. These stars were the home of the "fates," the Queen Marichi and all her attendants and the god of literature. Clearly, it was a crowded home!

The story begins one time when a young lad by the name of K'uei who was a literary student known for his great learning and brilliant wit. Unfortunately, K'uei was also rather ugly, so ugly in fact, that not even the most kindhearted person could help but shudder when their eyes fell upon him. So although K'uei was smarter than any before him, and witty, he had no friends.

At this time, it was customary for the emperor to present a golden rose to the winning candidate at the metropolitan examinations. As fate would have it, K'uei had won this honor. K'uei was very proud when he approached the throne but alas, when the emperor, even though he had been forewarned, laid his eyes upon the ugly K'uei, he dropped the rose and there it lay shattered.

Poor K'uei was in disgrace, and so, brokenhearted and finding life intolerable, he threw himself into the sea. As K'uei passed under the cool, calmness of the waves he was aware that under his feet had appeared a monster. The creature was one of those strange beasts who inhabit the depths of the sea, and he was lifting K'uei back up towards the surface.

The monster rose out of the waves with K'uei safely on his back and continued to mount higher and higher in the air, until at last he had reached the very sky itself. There, enthroned among the stars of the Bear, K'uei now watches over the literary affairs of the world and is the patron saint of all scholars.

Native American - Algonquin

There once was a very large and mean spirited old bear who's chief pleasure was to ravage a village. It seemed everyone was afraid of the bear who did more and more damage each time he attacked a village. Finally, the elders from many villages met to discuss what could be done about the bear. After they had smoked and talked for a long while they decided they would each bring their best and most brave warriors together to hunt the bear.

The three brave warriors all had done many things over time to show how strong and daring they were. When the bear realized just who was after him, he decided to run away because he was really a coward at heart. The bear ran and the hunters chased him.

The hunt went on for many moons and the bear began to tire. No matter what he did, he could not escape the hunters. Finally, in desperation, he ran right up into the sky and the hunters went right after him! Around and around they went, circling the north star.

Once, the lead hunter shot an arrow at the bear and managed to wound him, but the bear's magic was powerful and the wound was not fatal. But every autumn, as the bear and hunters circle low over the horizon, the wound bleeds a few drops of blood onto the Earth, and that is what makes the tree's leaves change colour every fall!

In England, Mizar and Alcor are called the horse and rider.

Observers

Sky Chart of North Circumpolar Stars

α Alpha Ursae Majoris (11h 04m +61° 45') - Dubhe, is a 1.9 magnitude yellow K0 giant star. It is 105 light years distant. Dubhe marks the top front of the bowl of the Big Dipper. It is about 105 times brighter than our Sun. It is also the only star that make up the Big Dipper that is not blue-white or blue. Another distinction that Dubhe, and Alkaid share is that they are the only stars in the Big Dipper that are not members of the Ursa Major moving cluster of stars. Dubhe has a very close fifth magnitude companion only one arcsecond distant and therefore cannot be resolved in amateur telescopes. Hindu astronomers knew Dubhe as one of Seven Sages, which were represented by stars of the Big Dipper. Dubhe is also one of the ponter stars that point to Polaris.

β Beta Ursae Majoris (11h 02m +56° 23') - Merak is a 2.4 magnitude blue-white class A1 star 60 light years distant. Merak is about 33 times brighter than our Sun and has a surface temperature of 10,200 deg K. Merak's spectrum displays very strong lines of hydrogen.

γ Gamma Ursae Majoris (11h 54m +53° 42') - Phecda is a 2.4 magnitude blue white class A0 main sequence star. Phecda is 80 light years distant. It is 50 times more luminous than our Sun with a surface temperature of 9,900 deg K. Every second, the distance between Phecda and our Sun decreases by 13 km.

ε Epsilon Ursae Majoris (12h 54m +55° 58') - Alioth is an average magnitude of 1.8 and is a blue-white, class A0 star, 80 light years distant. Alioth is the brightest star in the Big Dipper. It is a type of pulsating variable known as magnetic spectrum variables. Alioth has a surface temperature of about 9,900 deg K. It's magnitude varies between 1.76 and 1.79 over a period if 5.09 days. Alioth is about 80 light years from Earth.

ζ Zeta Ursae Majoris (13h 24m +54° 55') - Mizar, and it's companion star Alcor have a rich history of their own. Mizar has a magnitude of 2.1 and that of Alcor is 3.0. The pair are 90 light years distant. The pair have been used for a long time as a test of eyesight, as it takes very good eyesight to separate the stars with the unaided eyes! Mizar itself is a multiple system consisting of Mizar A and B. Mizar A is composed of two nearly identical blue-white main sequence stars of magnitude 2.0. This pair have a period of about 21 days. Mizar B is sixth magnitude and believed to be composed of three type A main sequence stars, but irregularities in the orbital path of Mizar B suggests the presence of yet another star with the period of 57 years.

η Eta Ursae Majoris (13h 48m +49° 19') - Alkaid or Benetnash is a 1.9 magnitude blue-white class B3 main sequence star 150 light years distant. The Arabs call this star the "principal mourner" of the children of Al Na'ash, who were murdered by the Pole Star, Al Jadi. According to the Arabic Myth, every night, the stars of the Plough or Big Dipper crowd around in their circumpolar course seeking revenge upon the Pole Star.

M51 (13h 29m +47° 18') - The Whirlpool Galaxy is located 3.5 degrees to the southwest of Alkaid. The galaxy has a magnitude of 8.

M81 (9h 54m +69° 09') This beautiful spiral galaxy has a magnitude of 8 and is about 10 degrees from Dubhe. The arms of M81 are very distinctive.

M82 (9h 54m +69° 47') This galaxy has an oval shape without distinctive arms.

M97 (11h 14m +55° 08') - The Owl Nebula is about 2 degrees southwest of Merak, with a magnitude of 11. It came to be known as the Owl Nebula because of the two circular markings in the nebula that look like the eyes of an owl. M97 is 12,000 light years distant. It is a planetary nebula with a shell of expanding gas around an aged star.

M101 (NGC 5457) (14h 01.4m +54° 35') This is perhaps the best example of a face on spiral galaxy visible to binoculars. It has a magnitude of 8.

M108 (NGC 3556) (11h 08.7m +55° 57') A spiral galaxy seen nearly edge on. It has a magnitude of 10.

M109 (NGC 3992) (11h 55.0m +53° 39') Dim spiral galaxy of magnitude 10.


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