: Earth , our 7 planets and hundreds of their satellites revolve around the star called Sun. With this the solar system. Just as a galaxy or galaxy is made up of a number of planets - satellites and the sun, such as the galaxy or the solar system , so galaxies are the habitation of the earth and other planets just as the galaxies are the habitation of the stars. Just as the planets revolve around the sun , the stars also revolve in their own orbits in the galaxy. The Milky Way galaxy is one such galaxy. And our Sun is a member star of this galaxy. Looking at the cloudless sky on a moonless dark night, one can see an enchanting combination of innumerable stars. If you look at the starry sky of such a dark night, you will see that a thin stream of light has gone from one horizon to another through the sky. This is the Milky Way galaxy. According to Greek mythology, the stream was born from the milk that fell from Juno 's breast when the goddess Juno was breastfeeding the baby Hercules . Hence its name Sarsudha. The Milky Way galaxy we live in is 90,000 light-years in diameter. The hydrogen and helium clouds that formed in the first 3 minutes of the creation of the universe are the building blocks of these new galaxies. References: Internet