I can't resist photographing M15 in the fall. This photo was made on the night of October 14, 2008, from my back yard. It is a composite of 20 two minute exposures at ISO 400, made with a Canon Digital Rebel XT.

M15 is a massive, very old globular cluster, about 33,600 light years from earth and estimated to be over 12 billion years old. It is a stunning sight through a telescope eyepiece at high magnification, and even more stunning in a well-resolved photo. M15 was the target of a photographic study by the Hubble Space Telescope in 1994, aimed at shedding light on how globular clusters form and what holds them together. The results are inconclusive so far, but some researchers believe that the stars in globular clusters were captured by the gravitational fields of black holes.