| Explanation |
Why is the sky near Antares and Rho Ophiuchi [ http://www.seds.org/billa/twn/antx.html ] 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.nasa.gov/apod/ap990829.html ]. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap000111.html ]. Backlit dust [ http://antwrp.gsfc.nasa.gov/apod/ap990509.html ] clouds block starlight and so appear dark [ http://antwrp.gsfc.nasa.gov/apod/ap990511.html ]. Antares [ http://antwrp.gsfc.nasa.gov/apod/ap980726.html ], a red supergiant [ http://www.lcse.umn.edu/research/RedGiant/ ] and one of the brighter stars in the night sky [ http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html ], lights up the yellow-red clouds on the upper left. Rho Ophiuchi [ http://antwrp.gsfc.nasa.gov/apod/ap960312.html ] lies at the center of the blue nebula on the right. The distant globular cluster [ http://antwrp.gsfc.nasa.gov/apod/globular_clusters.html ] M4 is visible just below Antares [ http://www.astro.wisc.edu/~dolan/constellations/hr/6134.html ], and to the left of the red cloud engulfing Sigma Scorpii [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992A%26A...261..203P ]. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ]. |
