Leo, the lion, springs across the sky on March nights. He’s in the east at nightfall, marked by his prominent “heart,” the bright star Regulus, which is a third of the way up the sky.
If you scan the sky below and to the left of Leo with a telescope, you’ll see clusters of galaxies. They contain thousands of galaxies in all. Each galaxy is an “island universe” similar to the Milky Way — a vast assemblage of millions or billions of stars.