... The Colorful Clouds of Rho Ophiuchi . ... The blue regions shine primarily by reflected light. Blue light from the star rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light. ... The Rho Ophiuchi star clouds , well in front of the globular cluster M4 visible on far lower left, are even more colorful than humans can see - the clouds emits light in every wavelength band from the radio to the gamma-ray. ... Publications with keywords: clouds . ...