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Monday 26 December 2011

What is a Galaxy?


General view of the people regarding the galaxy is a mystery, as to where is its end where its beginning is.



The universe in fact comprises of billions and billions of stars. And these stars are not distributed uniformly in the space. These stars do not occur in isolation as well. They are present in huge cluster, each clusters having billions and billions of stars. These clusters of stars are called galaxy.

                A Galaxy in fact is collection of billions of stars along with dust and hydrogen gas, separated in space from similar systems. These galaxies are the major building blocks of the universe.  In a galaxy the vast collection of stars are held together by a strong gravitational attraction. There are about 100 billion (1011) galaxies in the universe. With a galaxy comprising of 100 billion stars again. Thus there are approximately 1022 stars in the universe. We can’t see all the galaxies even with help of most powerful telescope. Only the nearest galaxies can be seen. The two important galaxies in the universe are:

1. Milky Way
2. Andromeda

 The sun and its family of planets belong to Milky Way galaxy. The Indian name of Milky Way is Akash Ganga. If you watch the sky in a moonless and cloudless night you will come across a huge strip of faintly glowing white light stretching across the sky from north to south. This huge strip has billions and billions of stars and our sun also belongs to this strip. The milky way which is our galaxy, is spiral type and not uniformly straight. 

The Andromeda galaxy was discovered by Persian astronomers. It is said that it is the biggest one amongst other local galaxies. It is located in Andromeda Constellation.

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