Pulsars, highly magnetized rotating celestial bodies, are considered candidates for ultra-high-energy cosmic ray sources. Due to their dense nature, pulsars generate strong gravity, leading astronomers to believe that planets can orbit them. However, the constant rotation speed of pulsars makes it difficult for astronomers to find their planets. The only way to detect pulsar planets is through pulsar timing, which involves precise instruments to detect changes in pulsar signals.

In 2000, astronomers discovered a planet called PSR B1620-26 b using pulsar timing. This gas giant planet has a mass 2.5 times that of Jupiter and takes nearly a century to complete one revolution around its host star. PSR B1620-26 b is estimated to be older than the Earth, making it one of the oldest known planets in the Milky Way galaxy. 

Its evolution remains a mystery, but astronomers speculate that it was captured by its pulsar host star from a white dwarf companion. As the pulsar absorbs material from the captured red giant star, it will eventually collapse into a white dwarf, possibly leading to interactions with other stars in the star cluster and the expulsion of the planet from its system. 

While PSR B1620-26 b has likely witnessed many cosmic events, its future may not be as bright, as it may become a wandering interstellar planet.