PSR B1257+12A is an extrasolar planet approximately 980 light-years away in the constellation of Virgo (the Virgin). The planet is the innermost object orbiting the pulsar PSR B1257+12, making the planet a pulsar planet. In 1997, it was claimed that this planet was in fact an artifact caused by solar wind, but this claim has since been disproved. It is about twice as massive as Earth's Moon.
It should be noted that 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 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 then the other two), the name "A" was commonly used. 51 Pegasi b (the first planet found around a Sun-like star), paved the way of naming planets. Though these pulsar planets were not renamed, some have taken the liberty to do it themselves. PSR B1257+12A is cataloged as "PSR 1257+12b" on the Extrasolar Planets Encyclopaedia.