1.2 Colorful Clouds of Rho Ophiuchi

The Rho Ophiuchi is surrounded by blue light, which occurs mainly due to reflected light. The yellow and red regions are due to the emission from the nebula's atomic and molecular gas. The dark regions are caused by dust grains, which block light emitted behind them. The M4 cluster is visible in the bottom right of the picture and emits the most colorful light, from nearly every wavelength, so not all of it can be seen with the naked eye.