Jocelyn Bell at Mullard Radio Astronomy Observatory Daily Herald Archive/SSPL/Getty

IN A way, it was the second signal that was the big one. The first signal I saw could have been a mistake. The second one meant this was something real. It took a while to realise what we had found: the very first pulsars, a new type of star. We’re still working out the true significance of the discovery today.

It was 1967, and we were looking for quasars using a radio telescope designed by Tony Hewish, my supervisor at the University of Cambridge. Back then, we knew only …