... Credit: D. Malin ( AAO ), AATB , ROE , UKS Telescope Explanation: Why is the sky near Antares and Rho Ophiuchi so colorful? ... Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae . ... Antares , a red supergiant and one of the brighter stars in the night sky , lights up the yellow-red clouds on the upper left. Rho Ophiuchi lies at the center of the blue nebula on the right. ... Publications with keywords: nebula - star formation - Antares . ...