A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems. A galaxy is held together by gravity. Our galaxy, the Milky Way, also has a super massive black hole in the middle.
Examples of galaxies range from dwarfs with as few as ten million stars to giants with a hundred trillion stars or more, each orbiting through their galaxy. There are probably more than 170 billion galaxies in the observable universe.
Some galaxies are spiral-shaped like ours. They have curved arms that make it look like a pinwheel. Other galaxies are smooth and oval shaped. They’re called elliptical galaxies. And there are also galaxies that aren’t spirals or ovals. They have irregular shapes and look like blobs. The light that we see from each of these galaxies comes from the stars inside it.
Image Credit: www.en.wikipedia.or