Discovery of Pulsars

(a) The first pulsar, CP 1919 , was discovered November 28, 1967, when its regularly spaced pulses (marked by ticks) were noticed in the output of a radio telescope. (b) Careful measurements of the pulsation period of pulsars reveal that most are slowing down.

Thus, their periods grow gradually longer. Glitches occur when a pulsar suddenly speeds up by a small amount. Here, three glitches in the pulsation of the Vela pulsar were recorded over an 8-year interval.