Sometimes when we look at the night sky, we can see a bright fuzzy band across the heavens. This is the Milky Way, our galaxy.
A galaxy is a collection of billions of stars. Most of the twinkling stars we see at night belong to the Milky Way. We can see only part of the galaxy, however. The Milky Way contains more than a hundred billion stars. Our sun is just one of them!
Where Are We?
Earth and the entire solar system are just a tiny part of the Milky Way galaxy.
The Milky Way has a spiral, pinwheel shape. Our solar system is located in one of its spiral arms, about two-thirds the distance from the center. We are closer to the edge of the galaxy than to the center.
Far Out!
To express the size of the Milky Way galaxy in miles, we would have to write a 6 followed by 17 zeroes!
Scientists prefer to measure cosmic distances in light-years. The Milky Way galaxy stretches 100,000 light-years from end to end. This equals the distance light travels in 100,000 years!
Of the millions of galaxies in the universe, ours is not the largest. In fact, the Milky Way is only a medium-sized galaxy.
Spiral Galaxy
The Milky Way galaxy contains billions of stars, nebulae, planets, moons, other bodies, and clouds of gas and dust. Observations show our galaxy to have a distinct central bulge, surrounded by a glowing halo.
Around this central bulge is a collection of star clusters, which surround the galaxy outside the galactic plane.
