"A lucid and engaging account of the scientific revolution that changed the way we think about our planet and ourselves."—James Lawrence Powell, author of Gra

"Radioactivity is like a clock that never needs adjusting," writes Doug Macdougall. "It would be hard to design a more reliable timekeeper." In Nature's Clocks,

Pulsars are rapidly spinning neutron stars, the collapsed cores of once massive stars that ended their lives as supernova explosions. In this book, Geoff McNama

Help children measure and tell time by the sun, the clock and the calendar; and learn why there are 24 hours in a day, 7 days in a week and 365 days in a year.