Original: 51 Pegasi b, also unofficially named Bellerophon and abbreviated as 51 Peg b, is an extrasolar planet approximately 50 light-years away in the constellation of Pegasus.
Simplified: 51 Pegasi b, also called Bellerephon or 51 Peg b, is the first extrasolar planet that was discovered orbiting a main-sequence star.