What if you could "see" gamma rays? This computer processed image represents a map of the entire sky at photon energies above 100 million electron Volts. These gamma-ray photons are more than 40 million times more energetic than visible light photons and are blocked from the Earth's surface by the atmosphere. In the early 1990s NASA's Compton Gamma Ray Observatory, in orbit around the Earth, scanned the entire sky to produce this picture. A diffuse gamma-ray glow from the plane of our Milky Way Galaxy is clearly seen across the middle. The nature and even distance to some of the fainter sources remain unknown. For more information see Compton Science Support Center release. We keep an archive of previous Astronomy Pictures of the Day. The sky is filled with breathtaking pictures, many of which are available on the World Wide Web. Each day we feature a different picture of some part of our fascinating universe, along with a brief explanation written by a professional astronomer. Astronomy Picture of the Day is brought to you by Robert Nemiroff and Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.