The Rosette Nebula (
NGC 2237) is
actually a collection
of
emission and
dark
nebulae. It got its name from
its distinct flowery shape.
In the hollowed-out centre of the nebula lies
an open cluster, NGC 2244, and the
young cluster (probably no more than
15,000 years old) is the reason for the nebula's
shape, as the radiation and stellar winds
from these star are blowing the gas and dust
away from the center. The hottest and youngest
of the stars have a surface temperature of
20,000 degrees, about 4 times as hot as our
sun.
On a clear winter night,
the cluster can be seen with the unaided eye,
but the entire nebula can be difficult to
see in small telescopes because of its large
size (it actually appears larger than the moon),
causing it to spill out of the field
of view.
The nebula and its cluster is between
3,000 and 4,500 light years away, and can
be found in the constellation Monoceros.