Astronomy Coursework Messier Objects

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The Messier objects[me.sje] are a set of 110 astronomical objects, of which 103 were included in lists published by French astronomer Charles Messier in 1771 and 1781.[1] Messier was a comet hunter, and was frustrated by objects which resembled but were not comets, so he compiled a list of them,[2] in collaboration with his assistant Pierre Méchain, to avoid wasting time on them. In addition to the 103 items published by Messier, seven more are thought to have been observed by Messier and have been added to the list by other astronomers over the years.

A shorter list had been published in 1654 by Giovanni Hodierna, but attracted attention only recently and was probably not known to Messier.[3][4]

Lists and editions[edit]

The first edition of 1771 covered 45 objects numbered M1 to M45. The total list published by Messier in 1781 contained 103 objects, but the list was expanded through successive additions by other astronomers, motivated by notes in Messier's and Méchain's texts indicating that at least one of them knew of the additional objects. The first such addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding a note Messier made in a copy of the 1781 edition of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.[5]M102 was observed by Méchain, who communicated his notes to Messier. Méchain later concluded that this object was simply a re-observation of M101, though some sources suggest that the object Méchain observed was the galaxy NGC 5866 and identify that as M102.

Messier's final catalogue was included in the Connaissance des Temps for 1784 (published in 1781).[6][7] These objects are still known by their "Messier number" from this list.

Messier lived and did his astronomical work at the Hôtel de Cluny (now the Musée national du Moyen Âge), in France. The list he compiled contains only objects found in the sky area he could observe: from the north celestial pole to a celestial latitude of about −35.7°. He did not observe or list objects visible only from farther south, such as the Large and SmallMagellanic Clouds.


The Messier catalogue comprises nearly all the most spectacular examples of the five types of deep-sky object – diffuse nebulae, planetary nebulae, open clusters, globular clusters, and 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 very small and visually spectacular details in them. A summary of the astrophysics of each Messier object can be found in the Concise Catalog of Deep-sky Objects.[8]

Since these objects could be observed visually with the relatively small-aperture refracting telescope (approximately 100 mm, or 4 inches) used by Messier to study the sky, they are among the brightest and thus most attractive astronomical objects (popularly called deep-sky objects) observable from Earth, and are popular targets for visual study and astrophotography available to modern amateur astronomers using larger aperture equipment. In early spring, astronomers sometimes gather for "Messier marathons", when all of the objects can be viewed over a single night.[9]

See also[edit]


External links[edit]

The Messier Catalog of
Deep Sky Objects

The Messier Catalog, sometimes known as the Messier Album or list of Messier objects, is one of the most useful tools in the astronomy hobby. In the middle of the 18th century, the return of  Halley's comet helped to prove the Newtonian theory, and helped to spark a new interest in astronomy. During this time, a French astronomer named Charles Messier began a life-long search for comets. He would eventually discover 15 of them. On August 28, 1758, while searching for comets, Messier found a small cloudy object in the constellation Taurus. He began keeping a journal of these nebulous (cloudy) objects so that they would not be confused with comets. This journal is known today as the Messier Catalog, or Messier Album. The deep sky objects in this catalog are commonly referred to as Messier objects.

The first of the Messier objects to be observed by Messier was the remnant of a supernova explosion known as the Crab Nebula (M1). Over the next few years, Messier and his colleagues would catalog a total of 110 nebulae, galaxies, and star clusters. Today, the Messier Catalog is a valuable tool for amateur astronomers. In fact, the "Messier Marathon" is somewhat of a rite of passage for those who are new to the hobby. Astronomy enthusiasts have been known to stay up all night in an attempt to observe all 110 Messier objects before the Sun rises the next morning.

Although many deep sky objects can display a wide array of colors in long exposure photographs, the human eye is not sensitive enough to see most of these colors through a small telescope. The photos in this section are presented in black and white to best represent the view that would be seen through a telescope. Many of these photos are copyright protected. Click here for copyright & source information. Click the link below to open the catalog or use the menus below to help locate a specific object within the catalog.

Begin exploring the Messier Object Catalog >>>

Messier Object Pages


Common Messier Objects by Name


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