M27: Not a Comet
Image Credit &
Copyright:
Francesco Sferlazza, Franco Sgueglia
While hunting for comets in the skies above 18th century France,
astronomer Charles Messier
diligently kept a list of the things
encountered during his telescopic expeditions
that were definitely not comets.
This is number 27 on his
now famous not-a-comet list.
In fact, 21st century astronomers would identify it as a
planetary
nebula, but it's not a planet either, even though it may
appear round and
planet-like in a small telescope.
Messier 27 (M27) is an excellent example of a gaseous emission nebula
created as a sun-like star runs out
of nuclear fuel in its core.
The nebula forms as the star's outer layers are expelled into
space, with a visible glow generated by atoms excited by the dying
star's intense but invisible
ultraviolet light.
Known by the popular name of the
Dumbbell Nebula,
the beautifully symmetric interstellar gas cloud
is over 2.5 light-years across and about 1,200 light-years away in the
constellation
Vulpecula.
This impressive color image highlights details within
the well-studied central region and fainter, seldom imaged
features in the nebula's outer halo.