This is surely one of
the finest galaxies in the sky. It was missed by Messier due to its
southerly declination and awaited discovery by William Herschel's sister
Caroline while hunting comets.
Part of the Sculptor group,
NGC 253 lies only about four times as far as the M 31 spiral in our local
group. Often photographed by amateurs and professionals alike, this galaxy
reveals vast lanes of dust, which are clearly visible in the HST image
below as dark brown streaks. The dust in a galaxy is often associated with
the clouds of gas that stars form out of. Its effect on our view is to
block the light of stars behind it and to scatter the blue starlight away,
making the stars appear more red than they really are. Notice the blue
clumps. Those are areas where stars have formed recently--the hottest stars
are generally brighter and appear blue. They are also the most massive.
The massive stars live very short lives compared to the others, so when
a cluster of stars has recently formed we see the light of the many bright,
blue stars. In time the blue stars will disappear. In this way the blue
regions in NGC 253 trace the places where stars are actively being formed
today.
NGC 253 is bright enough
to be visible in binoculars from a dark site, and even the smallest of
telescopes reveal a smaller version of M 31. In 8-inch or larger scopes
look for a mottling, particularly on the NW side. Due to its southerly
declination, NGC 253 does not rise high in the sky for northern latitudes.
For this reason it is best to observe it from these latitudes as it crosses
the meridian. In mid October NGC 253 crosses the local meridian at around
midnight local time.
Eyepiece view in 6-inch at
50x. North is down and east is to the right.
Larger scopes (16-inch
or greater) will clearly reveal the many thin lanes of dust. Their appearance
around the nuclear bulge can leave the viewer with a clear impression of
the apparent tilt of the galaxy. NGC 253 seen in one of these instruments
is one of the most unforgettable sights in the sky.
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