The Milky Way, our galaxy, is one of hundreds of billions (or trillions — who knows?) of tiny islands of stars sprinkled throughout the vast cosmic ocean of space. Seen from the top, galaxies are often shaped like flat spirals — children’s pinwheels of uncountable stars. Seen from the side, galaxies look much like lenses bulging at the center and tapering to points at the edges. Most of a galaxy’s stars are spread throughout the lens-like structure, the galaxy proper.