You may have noticed that many of the most photographed deep sky objects have
a popular name like Orion Nebula but also a catalog name and in the case of Orion Nebula
that would be M42 but what is this M in the M42? Well the M actually stands for Messier and
Messier is the astronomer who came up with this catalog and published it in this video i'm going
to explain who Messier was, what his catalog is all about, and why this Messier catalog
is still so popular today hundreds of years later Charles Messier was a French astronomer that lived
in the 18th century in Paris, France and he was obsessed with comets so much so that I think it'd
be perfectly fair to call him a comet hunter as his sort of occupation he discovered 13 comets in
his lifetime but Charles Messier he had a problem with his comet hunting he would often find these
nebulous faint fuzzy objects in the night sky and think that might be a comet only to observe it for
a little while and realize well it's not moving relative to the other stars so it must be some
fixed object out there in space at the time astronomy was visual only there was
before cameras and so and the telescopes weren't nearly as good as they are today
so there was no concept yet of other galaxies um what we now know are galaxies we're all
lumped in than with nebulae so it was the great nebulae and andromeda so to get back to the story
messier had an idea which is record a list of the positions of all these things that were definitely
not comets because they were fixed in the sky at first this was probably just for his own benefit
so he could quickly rule them out when searching for comets but at some point he started publishing
his lists in the french scientific journals and this was how Messier's catalog became one of the
first published catalogs of what we now call deep sky objects and partly because it was one of the
first it has had an enduring legacy even when later there were you know efforts to make much
more extensive catalogs of non-stellar objects like the new general catalog NGC even after that
the messier catalog was still a go-to for the objects that are included in it and let's talk
a bit now about what is included first off messier only observed from Paris, France so these are all
objects you can see from the northern hemisphere and some of them only from the northern hemisphere
there are only 110 objects included so for a point of comparison the NGC catalog has over
7000 but the great thing for us amateurs is all 110 objects in the Messier catalog were observed
with a 100 millimeter refractor from a rooftop in downtown Paris and this means that they're all
reasonably bright objects and because there are only 110 of them they make a really cool
challenge for instance my friends Galactic Hunter published a fun Messier Catalog Workbook
so you can check them off when you observe them or photograph them many people also try to complete
a messier marathon where in the spring you can actually try observing or photographing all 110
Messier objects in one night something i'd really like to try someday other than the compactness of
the list of just 110 objects i think another reason the messier catalog still remains so
popular is that many of the brightest showpiece objects in the northern sky are included in the
Messier catalog for us astrophotographers to name a few the lagoon nebula M8 hercules cluster
M13 the triffid nebula M20 the dumbbell nebula M27 the andromeda galaxy M31 the triangulum galaxy M33
the orion nebula M42 the whirlpool galaxy M51 the ring nebula M57 bodes and cigar galaxies M81
and 82 and the pinwheel galaxy M101 and all those ones i just listed would be a great starting list
for the beginner astrophotographer to take on then that's not to say that all the really photographic
objects are included in Messier's catalog for instance many of the large dim emission nebulae
that are very colorful that i like so much were invisible to messier but can be picked up a lot
easier with a long exposure on a camera well as always i could probably say more but this is five
minute friday so we're gonna end it here next week i'll be talking about ways to measure and compare
sky quality including some methods like light pollution maps the Bortle scale and sky quality
meters until next time this has been Nico Carver from nebulaphotos.com. Clear skies!