PSR B1257+12 B, also known as "PSR B1257+12 c" and Poltergeist, is an extrasolar planet orbiting the pulsar PSR B1257+12 approximately 2,300 light-years away from the Sun in the constellation of Virgo. It was one of the first planets outside of the Solar System to be discovered.
PSR B1257+12 B is over four times as massive as Earth. It circles the primary at a distance of 0.36 AU with an orbital period of around 66 days. Because it and PSR B1257+12 C have very similar masses and orbit close to eachother, they were expected to cause measureable perturbations in each other's orbits. Detecting such perturbations confirmed that the two planets were real.