When the horse was drinking from the well Pirene on the Acrocotinth, Bellerophon's fortress, the Corinthian hero was able to capture the horse by using a golden bridle, a gift from Athena. The gods then gave him Pegasus for killing the monster Chimera but when he attempted to mount the horse it threw him off and rose to the heavens, where it became a constellation (north of the ecliptic).
In another version, Bellerophon killed the Chimera while riding on Pegasus, and when he later attempted to ride to the summit of Mount Olympus, Zeus sent a gadfly to sting the horse, and it threw Bellerophon off its back.
