Editing Charles Messier (section)

==Messier catalogue==
{{see also|Messier object}}
[[File:M42m.jpg|thumb|right|The Orion Nebula as drawn by Messier, and which he gave the designation [[Messier 42|M&nbsp;42]] in his catalogue]]
Messier's occupation as a [[comet]] hunter led him to continually come across fixed diffuse objects in the night sky which could be mistaken for comets. He compiled a [[List of Messier objects|list of them]],<ref>{{cite web |date=25 February 2008 |title=The Messier Catalog |url=http://messier.seds.org/ |work=SEDS Messier Database |publisher=[[Students for the Exploration and Development of Space|SEDS]] |access-date=8 May 2010}}</ref> in collaboration with his friend and assistant [[Pierre Méchain]] (who may have found at least 20 of the objects<ref name=jones1991>{{cite book |first1=Kenneth Glyn |last1=Jones |year=1991 |title=Messier's nebulae and star clusters |issue=2 |series=Practical astronomy handbook series |edition=2nd |publisher=[[Cambridge University Press]] |isbn=0-521-37079-5 |page=5 |url=https://books.google.com/books?id=IuhLR35I9QUC&pg=PA5}}</ref>), to avoid wasting time sorting them out from the comets they were looking for. The entries are now known to be 39&nbsp;[[galaxies]], 4&nbsp;[[planetary nebula]]e, 7&nbsp;other types of [[nebula]]e, 26&nbsp;[[open cluster|open star cluster]]s and 29&nbsp;[[globular cluster|globular star cluster]]s.

Messier did his observing with a 100&nbsp;mm (four-inch) [[refracting telescope]] from Hôtel de Cluny (now the [[Musée national du Moyen Âge]]), in downtown [[Paris]], France. The list he compiled only contains objects found in the area of the sky Messier could observe, from the north [[celestial pole]] to a declination of about −35.7°&nbsp;. They are not organized scientifically by object type, or by location. The first version of Messier's catalogue contained 45&nbsp;objects and was published in 1774 in the journal of the [[French Academy of Sciences]] in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45&nbsp;objects being discovered by Messier himself.<ref>{{cite web |last1=Knight |first1=J.D. |title=Meet the Astronomers: Charles Messier |url=http://www.seasky.org/space-exploration/astronomers-charles-messier.html |website=Sea and Sky |access-date=2 September 2014}}</ref> By 1780 the catalog had increased to 80&nbsp;objects.

The final version of the catalogue was published in 1781, in the 1784 issue of ''[[Connaissance des Temps]]''.<ref>{{cite journal |first=Charles |last=Messier |year=1781 |title=Catalogue des Nébuleuses & des amas d'Étoiles |journal=Connoissance des Temps Pour l'Année 1784 (Published 1781) |pages=227–267 |bibcode=1781cote.rept..227M }}</ref><ref>{{cite web |title=Original Messier Catalog of 1781 |website=Messier.seds.org |url=http://messier.seds.org/xtra/Mcat/mcat1781.html#messier1781 |access-date=10 November 2007}}</ref><ref>{{cite web |url=http://messier.seds.org/xtra/history/m-cat81.html |website=Messier.seds.org |title=Charles Messier's personal copy of his 1781 "Catalog of Nebulae and Star Clusters"}}</ref> The final [[list of Messier objects]] had grown to 103. On several occasions between 1921 and 1966, astronomers and historians discovered evidence of another seven objects that were observed either by Messier or by Méchain, shortly after the final version was published. These seven objects, [[Messier 104|M&nbsp;104]] through [[Messier 110|M&nbsp;110]], are accepted by astronomers as "official" Messier objects.

The objects' Messier designations, from [[Crab Nebula|M&nbsp;1]] to [[Messier 110|M&nbsp;110]], are still used by professional and [[amateur astronomy|amateur astronomers]] today and their relative brightness makes them popular objects in the amateur astronomical community.