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Astronomy Picture of the Day
Orion's Horsehead Nebula
Bild Note: 3.5
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zorg.ch
#105604
by
[z]Barbara Harris
@
22.02.2008 00:00
- nach oben -
Orion's Horsehead Nebula
Explanation:
The
Horsehead
Nebula
is one of the most famous nebulae on the sky.
It is visible as the dark indentation to the red
emission nebula
seen just below
and left of center in the
this photograph
.
The brightest star on the left is located in the belt of the familiar
constellation
Orion
.
The
horse-head
feature is dark because it is really an opaque
dust
cloud that lies in
front of the bright red
emission nebula
.
Like clouds in
Earth's atmosphere
, this cosmic cloud has
assumed a
recognizable
shape
by chance.
After many thousands of years, the internal motions of the cloud
will alter its appearance.
The emission
nebula
's red color is caused by
electrons
recombining
with
protons
to form
hydrogen
atoms.
Also visible in the picture are blue
reflection nebulae
that
preferentially
reflect the blue light
from
nearby stars.
digg_url = 'http://apod.nasa.gov/apod/ap080221.html'; digg_skin = 'compact';
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