The milky way

            The milky way

The milky way is the name given to earth band of light that stretches across the night sky. This light comes from stars and nebulae in our galaxy, known as milky way galaxy or simply as “the galaxy”. The galaxy is believed to be a barred spiral, with a dense central bar of stars encircled by four arms spiraling outwards and surrounded by a less dense halo. We cannot see the spiral shape because the Solar system is one of the spiral arms, the Orion arm (also called local arm). From our position, the center of the galaxy is completely obscured by dust clouds; as a result, optical maps give only a limited view of galaxy. 
                                         OVERVIEW OUR GALAXY                                    
This is image overview our galaxy the milky way.
However, a more complete picture can be obtained by studying radio, infrared, and other radiation. the central part of galaxy is relatively small and dense and contains mainly older red and yellow stars .the halo is a less dense region in which the older stars are situated; some of these stars are as old as the galaxy itself(possibly 13 billion years ).the  spiral arms contain main sequence stars and hot, young, blue stars, as well as nebulae (clouds of dust and gas inside which stars born). The galaxy is vast, about 100,000 light years across (a light year is about 9,460 billion kilometres); in comparison, the solar system seems small, at about 12 light hours across (about 13 billion kilometres). The entire galaxy is rotating in space, although the inner stars out from the center, completes one lap of the galaxy about every 220 million years.

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