Nébuleuse de Rho Ophiuchi

It is one of the star forming regions closest to us. The whole complex covers 4.5 degrees by 6.5 in the sky. IC 4604 alone is nearly twice the diameter of the full Moon. The region mixes three things: dust that reflects, gas that emits, and dark clouds that hide. No narrowband filter suits all of it. It is the hours accumulated under a broadband filter that give it its colours.

Sources: Wikipédia en français, IC 4604, Wikipédia en anglais, Rho Ophiuchi cloud complex. A figure wrong? Report it.