Title:[1059] Stephan's Quintet Caption:This image of Stephan's Quintet was made by combining three CCD frames, taken at the Kitt Peak 4-m telescope in 1986. By using different filters in front of the monochrome detector, corresponding approximately to the primary colors red, green and blue, it is possible to recreate a true-color picture. Each image was processed to correct for detector sensitivity variations and to remove incorrect regions caused by manufacturing defects and by the arrival of cosmic rays at the telescope. Stephan's Quintet, as its name implies, is a collection of five galaxies: NGC 7317, 7318a, 7318b, 7319 and 7320, in the constellation of Pegasus. Due to a restricted detector size, this picture shows only four of the five galaxies (the fifth provides the ghostly glow on the right-hand edge of the frame). This unusual system has often been used as proof that the redshift is not truly a distance indicator - which would completely overturn current cosmology - because although four of the galaxies have similar, large redshifts, the fifth (NGC 7320), although apparently a member of the group, shows a much smaller redshift. Conventional theory states that the low-redshift galaxy is in a nearby group (the NGC 7331 group) and by coincidence appears on the sky projected against a distant background group. Opponents point to debris and tails around the low-redshift galaxy, suggesting that it is interacting with the high-redshift systems, which would require that all five galaxies be at the same physical location in space. The low-redshift galaxy towards the bottom of the picture is noticeably bluer than the pinkish high-redshift galaxies to the north. Such pictures are, of course, used as ammunition by both sides in the controversy. Copyright: Credit:National Optical Astronomy Observatories/W. Schoening/N. Sharp