... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2001 June 23 . The Cygnus Loop . Credit: J. Hester ( ASU ), NASA . ... The collision of this fast moving wall of gas with a stationary cloud has heated it causing it to glow in visible as well as high energy radiation , producing the nebula known as the Cygnus Loop (NGC 6960/95). ... Tomorrow's picture: Eight Burst Nebula . ... About APOD | ...