In December 2022, it will have been fifty years since humankind's last voyage to the Moon. And nations around the world have been gaining momentum, increasingly rapidly, in their planning to return. NASA proposes to land the first woman and next man on the Moon by 2024 (with the Artemis program) and to build a lunar orbiting space station - the Lunar Gateway - that will be capable of sustaining a permanent human presence by 2028. The Lunar Gateway is also meant to be a base for coordinating lunar development and function as a launch site for further solar system exploration (including to Mars and beyond). Meanwhile, the European Space Agency (ESA) has called for the installation of a permanent, human-inhabited village at the lunar southern pole. And, among other lunar projects, China's National Space Administration is also pursuing a human outpost on the Moon. Private entrepreneurs are enthusiastic about mining minerals on the Moon, making rocket fuel for further space exploration, and even developing luxury hotel resorts. These various lunar initiatives that characterize the new space race to the Moon are generally more commercial than scientific. Yet, geared as they are to establish habitable facilities on our nearest neighbor in space, they will also open up the Moon to science and usher in a new age of scientific exploration. While international space agencies and commercial interests jostle and race to create habitable space and profits on the Moon, this book advocates for the science that can be done there and lays out a vision for what the next fifty years of lunar science might look like. In particular, Silk advocates for the pursuit of lunar astronomy and argues that building a telescope on the lunar far side should be an integral part of plans to return to the Moon, as it would be uniquely poised to answer some of the most profound questions facing humankind: where did we come from and are we alone?