What is the Milky Way?

Our galaxy

The Milky Way is the name of our galaxy, a vast spinning disk of gas, dust, and stars, of which our own solar system is a part. Seen from Earth, the Milky Way appears as a bright band crossing the sky, made up of millions of stars too distant to be distinguished individually by the naked eye. Our galaxy contains about 100 to 400 billion stars and is constantly rotating, with the Sun taking about 250 million years to complete one orbit. The discovery of the structure and magnitude of the Milky Way has profoundly influenced our understanding of the universe and our place within it.