Explanation:
The 51st entry
in Charles Messier's famous catalog is perhaps the original
spiral
nebula - a large galaxy with a
well defined spiral structure also cataloged as NGC 5194.
Over 60,000 light-years across, M51's spiral arms and dust lanes
clearly sweep in front of its companion galaxy (right),
NGC 5195.
Image data from the Hubble's
Advanced Camera for Surveys has been
reprocessed to produce
this
alternative portrait of the
well-known interacting galaxy pair.
The processing has further sharpened details and enhanced color
and contrast in otherwise faint areas, bringing out
dust lanes and extended streams that cross the small companion, along
with features in the surroundings and core of M51 itself.
The pair are
about 31 million light-years distant.
Not far on the sky from the handle of the
Big
Dipper,
they officially lie within the boundaries of the small constellation
Canes Venatici.
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