Astronomers at the University of California, Santa Cruz, have developed a new technique to determine the ages of millisecond pulsars, the fastest-spinning stars in the universe. Ordinary pulsars tend to rotate a few times per second, and they gradually slow down with age, eventually becoming too faint to detect. Millisecond pulsars, however, rotate hundreds of time per second. They achieve these extraordinary spin rates by pulling in material from a binary companion star, a process that transfers angular momentum from the companion to the pulsar.