Black holes are one of the greatest mysteries of outer space. No visible light can escape the strong gravity of a black hole. This makes black holes invisible—and very difficult to study. But scientists make new discoveries and develop new theories about these mysterious objects every day. In 2015, astronomers were able to finally confirm a theory that Einstein had developed one hundred years earlier! And in 2016, scientists found that black holes may form in a different way than they ever thought possible. Read this book to learn more about the incredible and mind-boggling science of black holes.