Galaxies are the basic building blocks of the Universe. Their tiny points of light illuminate the vast cosmic architecture studded with giant superclusters surrounded by huge voids of nearly empty space. Each galaxy is a "star city" harboring up to a trillion stars. The gravity of a galaxy draws in fresh gas from its surroundings, which spawns new generations of stars. Supernova explosions over billions of years enrich the gas with oxygen, carbon, iron and other heavy elements, which are "cooked" only in massive stars. These heavy elements are the essential building blocks of planets such as Earth.

By these cycles of stellar birth and death, galaxies become fertile, self-sustaining ecosystems that evolve to become more and more suited for planets...and life. In essence, galaxies are the key agents by which the Universe builds complexity. Without them, the expanding cosmic soup would have diffused away into a sterile, featureless, and boring sea of gas.

Galaxy evolution is typified by long periods of calm punctuated by violent events such as the explosive growth of massive central black holes and disruptive collisions with other galaxies. These essential aspects of galactic history can be followed separately using the different telescopes of the multi-wavelength AEGIS database.

For example, images with the Hubble Space Telescope reveal the "morphological state" of a galaxy, whether quiescent and stable or disrupted by collisions with neighboring galaxies. The Chandra X-ray satellite and VLA radio data locate black holes buried in clouds of gas and dust clouds that Hubble cannot see. The GALEX and Spitzer satellites measure the rate of new star formation, including starbursts hidden by dust. Near-infrared images from the Palomar observatory enable AEGIS to measure the total stellar mass of galaxies. Optical spectra from the DEEP2 spectroscopic survey yield redshifts, distances, and look-back times, while CFHT photometry produces approximate redshifts and distances for galaxies too faint to be observed by DEEP2.