The discovery of pulsars, along with that of quasars and the cosmic microwave background, ranks among some of the most important discoveries in astronomy in the latter half of the twentieth century. The first pulsar was discovered in 1967 by Jocelyn Bell, Anthony Hewish, and their collaborators at Cambridge University. Bell's group was in the process of observing quasars, or distant, extremely bright galaxies whose source of energy to this day remains a bit of a mystery. In the astronomical data, Bell noticed an extremely regular, repetitive signal whose period was one and a third seconds. Its regularity led Bell and Hewish to first conjecture that the source was artificial, but after a careful search, they ruled out such a possibility and concluded that the pulses were astronomical in origin.

Currently there are about 1,000 known pulsars, similar to the one discovered by Bell and Hewish. The periods range from...