Blue Horsehead nebula (left) and Rho Ophiuchi nebula complex (right), one of the most colorful areas of the night sky. Rho Ophiuchi is the brightest of the three stars in the center of the blue reflection nebula at centre right. The gas and dust in this area are made visible by a variety of mechanisms. Yellow and blue regions are reflecting the light of the nearby stars. Red regions are caused by ultraviolet light from nearby stars exciting hydrogen gas. Darker regions are dense clouds and filaments of dust in front of the nebula that are seen in silhouette. Photographed from Cumeada Observatory, Reguengos de Monsaraz, Portugal.