The two most well known constalation are URSA MINOR( little bear ) and URSA MAJOR (big bear).Even as the most well know constalation not many peopel know the story behind them.The first story would be the one were Zeus the ruler of the greek gods fell in love with another women known as Callisto.She bore to him a son named Arcas.When Hera the greek queen of the gods saw how happy Callisto was in love with Zeus and in the growing handsomeness of her boy.Hera felt bitterly jealous.At last her anger and envy went beyond all bounds,and she changed Callisto into a bear.One day Callisto cought a glimpse in the distance of her own son Arcas,grown now to splendid manhood.Her love and yearning over came her,and she approached him with clumsy gait,she stood on her hind legs and sought to embrace him.But he drew back in mingled wonderment and alarm.As she persisted in following him,he raised up his spear and was about to kill the strange but terrifying animal.As the spearpoint was about to enter Callisto's breast,however, Zeus,looking down from the heavens,saw what was happening and in pity stayed the spear of Arcas.He snatched both of them and placed them as constellations in the sky.Callisto was called the Great Bear and her as Little Bear.Its also said,in ancient legends,that Hera complained bitterly to the gods of the sea at the way Zeus had treated her rival and rival's son:and these gods granted to her as a special favor that the Great Bear and the Little Bear should never come into their waters.

 

This is a Hubble Space Telescope image (right) of a vast nebula called NGC 604,which lies in the neighboring spiral galaxy M33,located 2.7 million light-years away in the constellation Triangulum.

This nebula is where new stars are being born in a spiral arm of the galaxy.Such nebulae are common in galaxies,this one is particularly large,nearly 1,500 light-years across.The nebula is so vast it is easily seen in ground-based telescopic images(left).At the heart of NGC 604 are over 200 hot stars,much more massive than our Sun (15 to 60 solar masses).They heat the gaseous walls of the nebula making the gas fluoresce.Their light also highlights the nebula's three-dimensional shape, like a lantern in a cavern.By studying the physical structure of a giant nebula,astronomers may determine how clusters of massive stars affect the evolution of the interstellar medium of the galaxy.The nebula also yields clues to its star formation history and will improve understanding of the starbrust process when a galaxy undergoes a "firestorm" of star formation.

The image was taken on January 17, 1995 with Hubble's Wide Field and Planetary Camera 2.Separate exposures were taken in different colors of light to study the physical properties of the hot gas (17,000 degrees Fahrenheit, 10,000 degrees Kelvin).

Credit: Hui Yang(University of Illionis) and NASA