The first confirmed planets outside the Solar System were found in 1992 by Aleksander Wolszczan and Dale Frail. They orbit PSR B1257+12, a pulsar: the collapsed core of an exploded star that sends out radio pulses at very regular intervals. The planets pull on the pulsar, so the pulses arrive a tiny bit early and late. Timing the pulses revealed the planets. Nobody expected planets around a dead star, and pulsar planets turned out to be rare.