This image of the sky around bright stars Antares (Alpha Scorpii) and Rho Ophiuchi (oh'-fee-yu-kee) reveals spectacular colors in a cosmic starscape. Near the top, blue light from the star Rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light. The Earth's daytime sky appears blue for the same reason. Cool supergiant star Antares (near the center) is itself shedding the material that reflects the evolved star's yellowish hue. The red regions shine primarily because of emission from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares - knocks electrons away from the gas, which then shines when the electrons recombine with the gas. The dark regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. About 500 light-years away, the Rho Ophiuchi star clouds, are well in front of the nearby globular star cluster M4, visible just below and right of center (text adapted from APOD).

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