Because we live on a rotating sphere, those of us in the Northern Hemisphere can’t see the part of the sky that includes Alpha Centauri. We can, however, catch a glimpse of the constellation Centaurus — named for the half-human, half-horse figure of Greek mythology. Its human form briefly rises above the southern mountains at shifting times throughout the year, including late evenings in May. Look due south for an arch of three stars marking the centaur’s head and arms.