Have you ever seen a galaxy? You can! Just look up on a moonless night. All the stars you see are part of the Milky Way galaxy. We live in the “suburbs,” or outskirts, of this galaxy. It’s made up of about 200 billion stars! The Milky Way has a central core that looks like a creamy stream across the black sky. (The Greek word for “milky” is galaxias.) That “creamy stream” is really billions of stars.
A galaxy is a huge swarm of stuff. It is stars, gas, dust, and dark matter held together by gravity. Stars circle, or orbit, around the center of a galaxy. The galaxy’s gravity holds stars in their orbits. The center of a galaxy has a lot of older stars. However, stars are a long way away from each other. The closest star to our Sun is Proxima Centauri. It’s about 25 trillion miles away! Strong telescopes show us that the universe has billions of galaxies. The biggest ones hold thousands of billions of stars. What other bodies “swim” in galaxies? How do galaxies form? New technology is helping astronomers learn more about our universe.
