Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2016 July 5
The Colorful Clouds of Rho Ophiuchi
Image Credit & Copyright: Tom Masterson, ESO's DSS
Explanation: The many spectacular colors of the
Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. 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. The red and yellow 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 brown regions are caused by
dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. The
Rho Ophiuchi star clouds, well in front of the
globular cluster M4 visible
hereon the upper right, are even more colorful than
humans can see - the clouds emits light in every
wavelength band from the
radio to the
gamma-ray.
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