‘The Crab’

Abstract

The discovery of the Crab and Vela pulsars put astronomers on the right track in deciding what pulsars were. The Crab pulsar, however, was to play an even more important role in pulsar astronomy. Aside from the intrinsic scientific interest of this object, it lies at the center of two stories of scientific priority. Priority — who discovered something first — is a big issue in science. Major discoveries always rely on technology (and hence technologists) and generally follow on from the work of others. Yet the fact remains that the scientist who gets their work into print earliest is given the credit for the discovery. An important and recurring factor in all this is not only making the right observations at the right time, but recognizing what you’ve seen. There are many examples of this in the story of pulsars, and perhaps none is more dramatic than the discovery of pulsars themselves. While Bell and Hewish have properly gone down in history as the discoverers of pulsars, pulsars were first detected, but not recognized, much earlier. Using an X-ray telescope, American astronomers had detected the pulsating signal from the Crab Nebula months prior to Hewish and Bell’s discovery; the trouble was, no one expected to find pulses in the observations and so, at least at first, no one thought to look. We’ll return to that story later, but first it is worthwhile to take a closer look at the discovery of the Crab pulsar, a discovery that unfolded in two episodes.