Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 November 1 Europa's Freckles Credit: R. Pappalardo (U. Colorado) et al., Galileo Project, JPL, NASA Explanation: Europa, one of Jupiter's large Galilean moons, may well posses an ocean of liquid water hidden beneath its icy surface -- and so holds the tantalizing possibility of life. In this image, constructed with data recorded in 1996 and 1997 by the Galileo spacecraft, Europa's characteristic surface ridges and cracks are...