world of astronomy ahead

What exactly a galaxy? A galaxy is a gravitationally bound stable system consisting of billions of stars, planets, dust, gases and remnants of other heavenly bodies. Some scientists believe that there could be as many as one hundred billion galaxies in the universe. Millions of stars together separated by a large distance from a galaxy. Nearly all large galaxies have a supermassive black hole at their centre.  Milky Way galaxy also has a supermassive black hole at its centre known as  Sagittarius A* . When we look up in the night sky we see the stars,  these are the stars that reside inside the milky way galaxy. if it's really dark, far away from the lights of the cities and buildings we can actually see the dusty band of the Milky Way stretch across the star. Types of galaxies 1.)  Spiral galaxy This is the class of galaxy in which the stars and gas clouds are mainly concentrated in one or more spiral arms. Most spiral galaxies are consist of a flat,...