The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer

Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects''. Messier's purpose ...

in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only interested in finding

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...

s, he created a list of those non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as ''the Messier catalogue''. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier numbers. The catalogue includes most of the astronomical

deep-sky object A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed fa ...

s that can easily be observed from Earth's

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

; many Messier objects are popular targets for amateur astronomers. A preliminary version first appeared in 1774 in the ''Memoirs'' of the

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at ...

for the year 1771. The first version of Messier's catalogue contained 45 objects which were not yet numbered. Eighteen of the objects were discovered by Messier, the rest being previously observed by other astronomers. By 1780 the catalogue had increased to 70 objects. The final version of the catalogue containing 103 objects was published in 1781 in the '' Connaissance des Temps'' for the year 1784. However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects. The catalogue consists of a diverse range of astronomical objects, from

star clusters Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clu ...

and nebulae to

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System ...

. For example, Messier 1 is a supernova remnant, known as the

Crab Nebula The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant and pulsar wind nebula in the constellation of Taurus. The common name comes from William Parsons, 3rd Earl of Rosse, who observed the object in 1842 u ...

, and the great

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:Andromeda Galaxy The Andromeda Galaxy (IPA: ), also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about approximately from Earth and the nearest large galaxy to the Milky Way. The gal ...

is M31. Further inclusions followed, the first addition came from

Nicolas Camille Flammarion Nicolas Camille Flammarion FRAS (; 26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction ...

in 1921, who added

Messier 104 #REDIRECT Sombrero Galaxy 104 104 may refer to: *104 (number), a natural number *AD 104, a year in the 2nd century AD * 104 BC, a year in the 2nd century BC * 104 (MBTA bus), Massachusetts Bay Transportation Authority bus route * Hundred and Four (o ...

after finding Messier's side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and

M109 The M109 is an American 155 mm turreted self-propelled howitzer, first introduced in the early 1960s to replace the M44. It has been upgraded a number of times, most recently to the M109A7. The M109 family is the most common Western indirect ...

by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.

Lists and editions

The first edition of 1774 covered 45 objects ( 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

in 1921, who added

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

by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967. 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 NGC 5866 (also called the Spindle Galaxy or Messier 102) is a relatively bright lenticular galaxy in the constellation Draco. NGC 5866 was most likely discovered by Pierre Méchain or Charles Messier in 1781, and independently found by William ...

and identify that as M102. Messier's final catalogue was included in the '' Connaissance des Temps pour l'Année 1784'' 'Knowledge of the Times for the Year 1784'' the French official yearly publication of astronomical ephemerides. Messier lived and did his astronomical work at the Hôtel de Cluny (now the Musée national du Moyen Âge), in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. The list he compiled contains only objects found in the sky area he could observe: from the north

celestial pole The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers a ...

to a celestial latitude of about −35.7° . He did not observe or list objects visible only from farther south, such as the

Large Large means of great size. Large may also refer to: Mathematics * Arbitrarily large, a phrase in mathematics * Large cardinal, a property of certain transfinite numbers * Large category, a category with a proper class of objects and morphisms ...

and

Small Small may refer to: Science and technology * SMALL, an ALGOL-like programming language * Small (anatomy), the lumbar region of the back * ''Small'' (journal), a nano-science publication * <small>, an HTML element that defines smaller text ...

Magellanic Clouds.

Observations

The Messier catalogue comprises nearly all the most spectacular examples of the five types of

– diffuse nebulae,

planetary nebula A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelate ...

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, an ...

globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

s, and

– 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''. Since these objects could be observed visually with the relatively small-aperture

refracting telescope A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses an ...

(approximately 100 mm ≈ 4 inches) used by Messier to study the sky, they are among the brightest and thus most attractive

astronomical object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''body'' are often u ...

s (popularly called

s) observable from Earth, and are popular targets for visual study and astrophotography available to modern

amateur astronomers Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers ...

using larger aperture equipment. In early spring, astronomers sometimes gather for "

Messier marathon A Messier marathon is an attempt, usually organized by amateur astronomers, to find as many Messier objects as possible during one night. The Messier catalogue was compiled by French astronomer Charles Messier during the late 18th century and co ...

s", when all of the objects can be viewed over a single night.

Messier objects

Star chart of Messier objects

References

External links