Poussieres sombres et nuages colores pres d'Antares
Image Credit:
David McGarvey
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 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 left of the featured image.
Rho Ophiuchi
lies at the center of the blue nebula near the top.
The distant globular cluster
M4 is visible to the right of Antares.
These star clouds are even more
colorful than humans can see,
emitting light across the electromagnetic spectrum.