PSR B1257+12 A - Name

Name

The planets of PSR B1257+12 are designated from A to D (ordered by increasing distance). The reason that these planets are not named the same as other extrasolar planets is mainly because of time. Being the first ever extrasolar planets discovered, and being discovered around a pulsar, the planets were given the uppercase letters "B" and "C" (like other planets). When a third planet was discovered around the system (in a closer orbit than the other two), the name "A" was commonly used. The extrasolar planet name 51 Pegasi b (the first planet found around a Sun-like star), was the idea used for naming planets. Although these pulsar planets were not renamed, some have done it themselves. PSR B1257+12A is catalogued as "PSR 1257+12b" on The Extrasolar Planets Encyclopaedia.

Further information: Extrasolar planet#Nomenclature