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. 2013 October 4 The Densest Galaxy Credit: NASA, ESA, Hubble Heritage Team (STScI/AURA), Jay Strader (Michigan St. Univ.) et al. Explanation: The bright core and outer reaches of giant elliptical ga..