The Bull was a constellation, an image drawn from stars by Andorians in the sky above Andoria. (TOS - Myriad Universes novel: The Tears of Eridanus)
History and specifics[]
An Andorian bull was an animal native to Andoria. (DS9 episode: "Fascination")
In the 23rd century, the constellation the Bull was visible alongside the Eagle and the Hybor when the gas giant Andor that Andoria orbited was a crescent in the sky. (TOS - Myriad Universes novel: The Tears of Eridanus)
Alternate timelines[]
Demora Sulu in 2292.
In an alternate timeline where Vulcans had remained a violent and emotional species, Hikaru Sulu and his daughter Demora moved to Andoria when Hikaru begun teaching at the Interstellar Institute in the 2270s decade. During the Andorian summer, Hikaru took Demora to the surface to the see the stars. The Bull was one of the constellations he pointed out to her.
In 2292, Commander Hikaru Sulu of the IUES Kumari II recalled that night while on a rescue mission to UGC 36A-2B, where Ensign Demora Sulu had gone missing. (TOS - Myriad Universes novel: The Tears of Eridanus)