When we look at the sky in the night, a dim strip of milky colour extending far and wide is seen. This is our Milky Way or ‘Akash Ganga’. With the help of the powerful telescopes, it has been observed that the Milky Way contains innumerable stars, dust and gases. Its milky colour is due to the presence of cluster of stars. The Solar System also belongs to this galaxy. There are billions of such galaxies in the universe.

            Scientists have studied the shape, size and structure of the Milky Way with the help of the powerful telescopes. It is like a lens, whose central part is very thick and edges are thin. Our Solar System is situated at the thin edge. When we look at the sky, we are, in fact, looking at the centre of the Milky Way. That is why the stars present in it seem to have clustered together. Studies have revealed that the Milky Way is spiral-shaped. It has around 150 trillion stars.

            Do you know the size of the Milky Way? Its size can not be measured in terms of kilometres. There is a separate unit for measuring large distances. This unit is called a light year, which is the distance travelled by light in a year. We know that light travels with a velocity of 30 thousand km per second. In a year, it will travel a distance of 9 million km. This distance is called one light year. The diameter of Milky Way is one hundred thousand light years. The sun is located at a distance of 30 thousand light years from the centre of the Milky Way. Our sun also revolves around this Milky Way and takes 225 million years to complete one revolution.

            If we look carefully at the Milky Way, some black parts are also seen. These are the regions which have less stars and more dust.