Astronomy Picture of the Day

When Roses Aren't Red

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#85416 by @ 25.03.2006 00:00 - nach oben -
When Roses Aren't Red


Not all roses are
red of course, but they can still be very pretty.

Likewise, the beautiful
and other star forming regions are often shown in
astronomical images
with a predominately red hue - in part because the dominant
emission in the nebula is
from hydrogen atoms.

Hydrogen's strongest optical
emission line, known as H-alpha,
is in the red region of the spectrum, but the beauty of an
emission nebula need not be appreciated
in red light alone.

in the nebula are also excited by energetic
and produce narrow emission lines as well.

In this
gorgeous view
of the Rosette's central regions,
narrow band images are combined to show
emission from sulfur atoms in red, hydrogen in blue, and
oxygen in green.

In fact, the
scheme of mapping these narrow atomic
emission lines into broader colors is adopted in
many Hubble images
of stellar nurseries.

This image spans about 50 light-years in
the constellation Monoceros, at the 3,000 light-year
distance of the

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