Barnard's Loop nebula in Orion. Enhanced optical image of Barnard's Loop (red), a broken ring of nebulosity in the constellation Orion. The large round nebula at upper centre is Sh2-264. The Great Orion nebula (M42) is bright yellow at lower centre. The constellation Orion contains several bright stars, including Rigel (blue, lower right) and Betelgeuse (upper left). The loop nebula formed as new, hot stars caught nearby gas and dust in a pressure wave, forcing them into a glowing, expanding ring. This image was produced by a CCD (charge-coupled device) camera, which stores images electronically rather than on film.