Editing Messier object (section)

==Observations==
The Messier catalogue comprises nearly all of the most spectacular examples of the five types of [[deep-sky object]] – [[diffuse nebulae]], [[planetary nebula]]e, [[open cluster]]s, [[globular cluster]]s, and [[galaxy|galaxies]] – visible from European latitudes. Furthermore, almost all of the Messier objects are among the closest to Earth in their respective classes, which makes them heavily studied with professional class instruments that today can resolve small and visually significant details in them. A summary of the astrophysics of each Messier object can be found in the ''Concise Catalog of Deep-sky Objects''.<ref>
{{cite book |last=Finlay |first=W. H. |title=Concise Catalog of Deep-sky Objects: Astrophysical information for 500&nbsp;galaxies |date=2003 |publisher=[[Springer (publisher)|Springer]] |isbn=1-85233-691-9}}</ref>

Since these objects could be observed visually with the relatively small-aperture [[refracting telescope]] (approximately 100&nbsp;mm ≈ 4&nbsp;inches) used by Messier to study the sky from downtown [[Paris]], they are among the brightest and thus most attractive [[astronomical object]]s (popularly called [[deep-sky object]]s) observable from Earth, and are popular targets for visual study and [[astrophotography]] available to modern [[amateur astronomy|amateur astronomers]] using larger aperture equipment. In early spring, astronomers sometimes gather for "[[Messier marathon]]s", when all of the objects can be viewed over a single night.<ref>
{{cite web
 |date=19 March 2013
 |title=The Messier Marathon
 |url=http://messier.seds.org/xtra/marathon/marathon.html
 |publisher=[[Students for the Exploration and Development of Space]] (SEDS)
 |access-date=17 May 2014
}}
</ref><ref>
{{cite book
 |last1=Stoyan |first1=Ronald
 |last2=Binnewies |first2=Stefan
 |last3=Friedrich |first3=Susanne
 |title=Atlas of the Messier Objects: Highlights of the Deep Sky
 |date=2008
 |publisher=Cambridge University Press
 |isbn=9783319977072
}}
</ref>