The Incredible Shrinking Planet
Where I live in the Rocky Mountains, you can see several thousand stars with the naked eye on a clear night. All of them belong to the Milky Way Galaxy, which contains more than 100 billion stars, including an average-sized one that our planet Earth orbits around—the Sun. Our galaxy has plenty of room: 26 trillion miles separate the Sun from the star nearest to it. And traveling at the speed of light, it would take you 25,000 years to ...