PSR B1257+12 b

PSR B1257+12 c, alternatively designated PSR B1257+12 B, also named Poltergeist, is an extrasolar planet approximately 2,300 light-years away in the constellation of Virgo. It was one of the first planets ever discovered outside the Solar System, and is one of three pulsar planets known to be orbiting the pulsar PSR B1257+12.
Over four times as massive as the Earth, it circles the primary at a distance of 0.36 AU with an orbital period of approximately 66 days. Because it and Phobetor have very similar masses and orbit close to each other, they were expected to cause measurable perturbations in each other's orbits. Detecting such perturbations confirmed that the planets were real. Accurate masses of the two planets, as well as their inclinations, were calculated from how much the planets perturb each other.
== Nomenclature ==
Using the letters PSR (Pulsating Radio Source) was followed by the pulsar right acension and degrees of inclination that arose for designating pulsars.
== See also ==
* Pulsar
* Pulsating radio source
* List of exoplanets#before 2000