The document discusses the top 10 photographs taken by the Hubble Space Telescope over its 16 years in operation. It begins by providing context about the Hubble telescope and light years as a measurement of distance. It then lists and provides brief descriptions of each of the top 10 photographs, which include images of galaxies like the Sombrero Galaxy and nebulae like the Ant Nebula, Eskimo Nebula, and Hourglass Nebula.