From National Georgaphic.com:

While she was a graduate student and junior researcher in radio astronomy at Cambridge University in England, Jocelyn Bell Burnell made a discovery that changed science. In 1967, she was given the mind-numbing task of analyzing three miles of printed data from a radio telescope she helped assemble. That’s when she noticed recurring signals, later called pulsars. These were given off by the rotation of small stars leftover from huge stars that went supernova.

Her discovery was important because it proved that once supernova happened, the stars didn’t disappear, but rather left behind dense rotating stars.

Despite Jocelyn’s contribution, the 1974 Nobel Prize in Physics was awarded to her supervisor, Anthony Hewish, and another Cambridge radio astronomer, Martin Ryle.