The Lagoon Nebula (also M8, and NGC 6523) in the constellation Sagittarius is well-known to amateur astronomers. It is a giant star forming region with an open cluster of stars embedded within (visible on the right side of the image). A giant O-type star pumps out massive amounts of ultraviolet light that energizes the gasses in the nebula and cause them to emit light in their distinctive characteristic colors. By taking images through emission line filters, astronomers can see what elements are contained in the nebula. In this image made with Hydrogen-alpha, Sulfur II, and Oxygen III filters, the bluish glow of ionized Oxygen predominates in the center of the nebula.