Stars, Dust, and Gas Near Antares

Explanation: Why is the sky near Antares and Rho Ophiuchi so dusty yet colorful? The colors result from a mixture of objects and processes. Fine dust -- illuminated from the front by starlight -- produces bluereflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and soappear dark. Antares,a red supergiant and one of the brighter stars in the night sky, lights up the yellow-red clouds on the lower right of the featured image. The Rho Ophiuchi star system lies at the center of the blue reflection nebula on the top left. The distant globular cluster of starsM4 is visible above and to the right of Antares. These star clouds are even more colorful than humans can see,emitting light across the electromagnetic spectrum.

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Explanation: South of the large star-forming region known as theOrion Nebula, lies bright blue reflection nebulaNGC 1999. At the edge of theOrion molecularcloud complex some 1,500 light-years distant, NGC 1999'sillumination is provided by the embedded variable star V380 Orionis. The nebula is marked with a dark sideways T-shape at center right inthis telescopic vistathat spans about two full moons on the sky. Its dark shape was once assumed tobe an obscuring dust cloud seen in silhouette. But infrared datasuggest the shape is likely a hole blown through the nebulaitself by energetic young stars. In fact,this region aboundswith energetic young starsproducing jets and outflows with luminous shock waves. Cataloged as Herbig-Haro (HH) objects, named for astronomersGeorge Herbig and Guillermo Haro,the shocks have intense reddish hues. HH1 and HH2 are just below and right of NGC 1999. HH222, also known as theWaterfall nebula,looks like a red gash near top right in the frame. To create the shocks stellar jets push throughthe surrounding material at speeds ofhundreds of kilometers per second.