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.