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Terme du glossaire : Objet Messier

Description : Un objet Messier est l'un des 110 objets répertoriés pour la première fois par Charles Messier et Pierre Méchain en 1781. Messier et Méchain cherchaient des comètes, qui apparaissent floues et étendues, mais ils ont trouvé de nombreux objets flous et étendus qui ne semblaient pas bouger. Ils ont catalogué ces objets afin de ne pas perdre de temps d'observation s'ils les observaient à nouveau. Ces objets flous et étendus situés au-delà de notre système solaire ont été baptisés "nébuleuses".

Dans sa forme actuelle, le catalogue contient 55 amas d'étoiles, 39 galaxies, 11 vraies nébuleuses et cinq groupes d'étoiles. Ces objets sont les cibles préférées des astronomes amateurs. Compilé par Messier pour éviter des erreurs, ces objets sont des trésors pour les astronomes amateurs.

Les objets Messier sont souvent désignés par leur numéro de catalogue précédé de la lettre "M". Ainsi, la galaxie spirale Messier 101 est souvent appelée M101.

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Media associé


A cluster of brilliant blue stars illuminate the surrounding nebular gas.

The Pleiades M45 with Majestic Dust

Légende : Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   Taken in Dar Eid in Saint Catherine/Sinai, Egypt, in October 2021, this image shows the Pleiades, an open cluster also known as The Seven Sisters. The Pleiades are located in the north-western part of the constellation Taurus, the Bull. This constellation originates from ancient Babylonian or even Sumerian belief, where it was designated the Bull of Heaven, a mighty creature owned by the sky god. In Late Babylonian times, the Pleiades were called The Bristle at the hunchback of The Bull. In China, the asterism is also called The Hair, but this does not necessarily imply any relationship between the East Asian and West Asian names of this asterism, although exchange is hypothesised with the establishment of the Silk Road. In ancient Babylonian texts the term The Hair does not appear. Instead, the Pleiades are only called The Star Cluster in Sumerian, and the Sumerian term was used in later languages as a loanword. The Sumerian and early Babylonian religion associated all constellations with specific deities, including gods, demons, messengers of gods. The Star Cluster was associated with a deity of the Netherworld that was called The Seven and was considered an ensemble of seven speaking weapons or strongly armed gods. The later Greek name of the Seven Sisters might possibly have sprung from an intercultural misunderstanding of this older religious association, since, in fact, seven stars are not seen in this cluster. The star cluster of the Pleiades is really prominent in the sky, and thus was used for several cultural purposes, such as determining the calendar and the spring equinox. However, its significance is frequently overstated in cultural astronomy. As the tradition of representing it with seven dots originates from an ancient Sumerian belief, we should be careful about interpreting any group of seven dots on cave walls and archaeological sites across Europe, Asia and America from the Stone Age onwards as a representation of the Pleiades. Modern astrophysics has found that the star cluster of the Pleiades is extraordinarily young, so there was certainly not an additional star in ancient times. Furthermore, we know that the bright stars are only the core region of an open star cluster that consists of hundreds of stars scattered over an area of the sky which exceeds the bright core by one or two of its diameters in any direction. The photograph does not even show the whole cluster. The group is thought to be about 400 light-years away from Earth, which is relatively close in astronomical terms.
Crédit : Mohamed Usama/IAU OAE

License: CC-BY-4.0 Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes


Andromeda is a bright disk, with dark spiral lines in it, tilted up at the west end. Two small bright blobs lie left & right

A visible light image of the Andromeda Galaxy

Légende : The Andromeda Galaxy viewed in visible light. Like our Milky Way, Andromeda is a barred spiral galaxy. Here we can see its bright core and spiral disk. The glow from the stars in the disk is interrupted by lanes of dust that form part of its spiral structure. Andromeda is the largest galaxy in the Local Group of galaxies that includes the Milky Way. To the left of the core and just above the disk we see the dwarf galaxy M32 and to the right and below the disk we see the dwarf galaxy M110. These are both satellite galaxies of the Andromeda Galaxy.
Crédit : Torben Hansen Lien vers les crédits

License: CC-BY-2.0 Creative Commons (CC) Attribution 2.0 Générique Icônes

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