The age of the Earth has been one of the most disputed numbers in science since the 17th century. Although most earth scientist and astronomers accept the Earth's age to be 4.55 billion years, much significance lies in the manner in which that figure was determined. Transmuted Past follows the development of theories of stellar evolution and nucleosynthesis in the 20th century and describes radiometric methods for estimating the age of the Earth. Throughout the 19th and 20th centuries, the reputation of the planetary sciences changed significantly; whereas the planetary sciences once played an integral role in science, they eventually came to be accorded a status inferior to atomic physics and cosmology. Professor Brush explores this shift and shows how a planetary science such as geology can provide a useful example of the scientific approach for comparison with a humanistic discipline such as history.