Astronomers define a planet as an object that orbits the sun (but not another object), is round (or nearly so) and has cleared the area around its orbit.| Space.com
We are living in a golden age of Milky Way research and exploration.| Space
Earth is the only planet known to support life. Learn about what Earth is made of and where it came from.| Space
Explore our solar system's planets from the nearest to the sun to the furthest.| Space.com