The Trifid Nebula

About This Photograph

Appearing in a dense region of the summer Milky Way we find the Trifid Nebula star-forming region. Most such regions are seen mainly by gas stimulated to emit its own light by the ultraviolet light of bright stars within, forming an emission nebula. But in the Trifid, the area of blue nebulosity is composed of material that is seen simply by being illuminated by nearby starlight, a reflection nebula. Silhouetted in front of both of these areas we find dark veins and patches. These are denser areas of gas and dust that block light from beyond, known as absorption nebulae.