Do you like to gaze at the stars? So did the young Stephen Hawking. Eventually, he turned his fascination with the night sky into a career of trying to figure out how the universe began and how it works.

As a child, Hawking loved the stars and he loved math class. In college, he studied physics and cosmology, or how the universe came to be. But then he was diagnosed with amyotrophic lateral sclerosis (ALS), a disease that shuts down the nerves that control muscles. His doctors thought he had two years to live, so Hawking started working hard to meet his goals. He studied black holes and made discoveries that earned him recognition around the world. He wrote several books about the universe to help people understand his ideas. More than fifty years after his diagnosis, Hawking still has ALS, but he continues to ponder the night skies, trying to find one theory that will explain the universe.