Arkab Prior

Its story

Arkab Prior is a blue class-B star lying 313 light-years away in Sagittarius, the leading half of an optical pair that shares its name with companion Arkab Posterior. Its Arabic name, «al-'urqub», means «the hamstring», describing the rear leg of the celestial centaur. Visually close yet physically unrelated by gravity, the two Arkabs show how easily human perspective is fooled when trying to read depth in a sky without distance.