Stephen Hawking’s Snapshots of the Universe is an app that teaches users about the principles that control our universe. It covers a variety of things – including why planets stay in orbit, why stars aren’t always located where we think they are, and how our understanding has evolved over time. It also covers topics like black holes, time, and gravity. The app is now available to purchase for $4.99.

“This app provides a great opportunity to introduce Professor Hawking’s teachings to a whole new audience, through an entirely new medium,” said Scott Shannon in a press release, the Senior Vice President and Publisher of Digital Content at Random House. “We are very proud to continue our publishing tradition with Professor Hawking, now across more platforms than ever.”