Why is the sky near Antares and Rho
Ophiuchi so colorful? The colors result from a mixture of objects and
processes.
Fine dust illuminated from the front by starlight produces
blue reflection nebulae.
Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae.
Backlit dust clouds block starlight and so appear dark.
Antares,
a red
supergiant and one of the brighter
stars in the night sky, lights up the yellow-red clouds on the lower
center.
Rho
Ophiuchi lies at the center of the blue nebula near the top.
The distant globular cluster M4 is visible just to
the right of Antares,
and to the lower left of the red cloud engulfing Sigma Scorpii.
These star clouds are even more colorful than
humans can see, emitting light across the electromagnetic
spectrum.
Image Credit & Copyright: Tom
O'Donoghue