But the Antennae galaxy is close enough to answer some fundamental questions about the clusters. The Antennae has two long wisps extending from a central heart-shaped core. The galaxy got its name because the wisps of dust and stars resemble the antennae of insects. The new pictures may settle a long-term controversy among astronomers about how the two basic types of galaxies formed. Spiral galaxies, such as the Milky Way, have long curving arms of stars and dust, rotating about a center.
Elliptical galaxies are oval and more compact, lacking the arms.
Based on the Hubble photos, the astronomers said it is now clear that elliptical galaxies are formed when two spirals collide. Though such a collision is enormously violent, it takes almost a half-billion years before the merging spiral galaxies settle down into a single elliptical that may contain a billion stars.