PSR B1620-26 b was discovered in 1993 using the pulsar timing method. This technique involves detecting the slight irregularities in the precise timing of pulses emitted by a pulsar (a rapidly spinning neutron star). Pulsars emit regular bursts of radio waves, but if they are orbited by a planet, the planet’s gravitational pull causes a slight delay in these pulses. The planet was found in a binary system where a pulsar and a white dwarf star orbit each other. By measuring the timing variations of the pulsar’s radio waves, astronomers inferred the presence of PSR B1620-26 b, confirming it as one of the oldest known planets.