skyeye
M27: Not A Comet

While searching the skies above 18th century France for comets, astronomer
Charles Messier diligently recorded this object as number 27 on his list of
things which are definitely not comets. So what is it? Well, 20th century astronomers
would classify 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 now known
to be 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 about 1,200 light-years away in the
constellation Vulpecula. This gorgeous synthetic color picture of M27 was produced
during testing of one of the European Southern Observatory's Very Large Telescopes.