The Milky Way is a large band of stars, dust and gas that make up our galaxy. It contains billions of stars. Our sun and the solar system is only one of them. The Milky Way is only one of billions of galaxies that make up our universe. It has a diameter of about 100,000 light years and is as old as the universe itself. The name probably refers to how we see our galaxy - a white blurry band that looks like spilled milk.
The Milky Way has the shape of a thin disk with six spiral arms coming out of a bulge in the center . This bulge consists of a cluster of large stars, gas and dust as well as a strong magnetic field. The whole galaxy rotates around this inner bar of stars. New stars areconstantly formed around the spiral arms. Most of the stars in our galaxy are red dwarfs, cold stars that are much smaller than our sun.
The galaxy gets flatter towards the edges. The center of the Milky Way consists of a black hole; an invisible object that has such a strong gravitational pull that not even light cannot escape. The galaxy is surrounded by a gigantic halo made up of old stars and gas that stretches hundreds of thousands of light years into the universe.
Our solar system is located on the inner edge of one of the spiral arms, about 30,000 light years from the centre. It completes one orbitaround the centre about every 240 million years.
Astronomer Edwin Hubble was the first to find out that the Milky Way is only one of many galaxies in our universe. The nearest is Andromeda, which is often referred to as our sister galaxy. It is estimated that in about 4 billion years the Milky Way and Andromeda willcollide.
