This is a color composite image made by Karen Gloria at Hopkins Observatory using a 6-inch refractor and a 512x512 element CCD detector. M16 is a young stellar cluster where the radiation of hot stars causes the surrounding hydrogen gas to become ionized. When the electrons and protons recombine a red emission line is given off. The blue nebulosity in this image is associated with preferential scattering of blue light by dust. M16 has an overall angular size of approximately 1/2 a degree.