Galaxies

A galaxy is a large conglomeration of stars, gas, and dust that are all gravitationally bound in a distinct formation. But while distinct, these formations can take on different characters. Some galaxies show distinct spiral arms. Others look simply like large oblate blobs. Some are irregular in shape and composition. And still others are a combination of these shapes and configurations. Galaxies are the basic building block of the universe and contain the vast majority of its visible matter.