The Hubble Deep Field reveals an endless array of galaxies in every direction, each of which is filled with billions of stars and possible sites for habitable planets. Source: with permission from NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI).