Why is the sky near Antares and Rho Ophiuchi [ http://www.seds.org…] so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae [ http://antwrp.gsfc.…]. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae [ http://antwrp.gsfc.…]. Backlit dust [ http://antwrp.gsfc.…] clouds block starlight and so appear dark [ http://antwrp.gsfc.…]. Antares [ http://antwrp.gsfc.…], a red supergiant [ http://www.lcse.umn…] and one of the brighter stars in the night sky [ http://www.astro.wi…], lights up the yellow-red clouds on the upper left. Rho Ophiuchi [ http://antwrp.gsfc.…] lies at the center of the blue nebula on the right. The distant globular cluster [ http://antwrp.gsfc.…] M4 is visible just below Antares [ http://www.astro.wi…], and to the left of the red cloud engulfing Sigma Scorpii [ http://adsabs.harva…]. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum [ http://imagine.gsfc…].
