While hunting for comets in the skies above 18th century France,
astronomer Charles Messier
diligently kept a list of the things
he encountered that were definitely not comets.
This is number 27 on his
famous not-a-comet list.
In fact, 21st century astronomers would identify it as a
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
Known by the popular name of the
Nebula, the beautifully
symmetric interstellar gas cloud is over 2.5 light-years across and
about 1,200 light-years away in the
This impressive color composite highlights details within
the well-studied central region and fainter, seldom imaged
features in the nebula's outer halo.
It incorporates broad and narrowband images
filters sensitive to emission from sulfur, hydrogen and oxygen atoms.