English: The Dumbbell Nebula, Messier object 27 (M27), NGC 6853, in the constellation Vulpecula, as seen by the Kitt Peak 4-meter Mayall telescope in 1988. This false colour image was made from a combination of two CCD frames, taken at the Kitt Peak 4m telescope in 1988. 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. The red filamentary structure comes from H-alpha emission, imaged using a very narrow filter tuned to exactly the right wavelength. The green, broader and more diffuse, structure was imaged using a filter chosen to show the general (``continuum) emission from the nebula. The blue structure is a composite of the green and the red, but processed to show the fainter features surrounding the brighter inner area of the nebula. The Dumbbell Nebula (M27, NGC 6853) is a planetary nebula in Vulpecula, whose central blue star (only just visible in this picture) continues to ionize the surrounding gas. The designation is now a historical curiosity, as these nebulae are believed to be a normal stage in stellar evolution involving the expulsion of significant matter back into the interstellar medium, and not to be connected in any way with the formation of planetary systems. The nebula is about 850 light-years away and 1.5 light-years across, but these numbers are not known very accurately because it is intrinsically very hard to determine the distance of any planetary nebula.