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Credit & Copyright: Anglo-Australian Telescope
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Explanation:
What causes the colors in this beautiful nebulosity in Sagittarius?
Dubbed NGC 6589 and NGC 6590,
the colors of this nebulosity,
are caused by gas and
dust.
The blue color of the nebula nearest the bright stars is caused by reflection off interstellar dust. The dust emits little visible
light of its own - in the absence of a nearby star the dust would appear
dark, blocking light from
background stars. The red color of the
nebula furthest from the bright stars is caused by glowing hydrogen gas.
Energetic light
from the central stars ionizes
hydrogen gas
-
which glows red when recombining with a local electron. In the absence of
a nearby star, the gas would neither glow on its own nor absorb much
background starlight.
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NASA Official: Jay Norris. Specific rights apply.
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& Michigan Tech. U.
Based on Astronomy Picture
Of the Day