Facts About the Messier Objects Catalog

Facts About the Messier Objects Catalog
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What Was Charles Messier Trying To Accomplish?

In the late 18th century, Charles Messier (1730 - 1817) was trying to study comets, but his views were confounded by other objects, and these other objects were not comets; they were diffuse objects that had some comet characteristics but more often than not did not have enough of those characteristics, for example, they showed very little movement through space. He created a catalog of objects, which purpose was to help comet hunters so they could distinguish between permanent objects in the sky and the more transient objects.

Facts About The Messier Catalog

The catalog was published in three installments beginning in 1774, it covered objects M1 through M45. A supplement was published in 1780 covering objects up to M68. The final supplement was published in 1781 and covered objects up to M103. He was assisted in his endeavor by his friend and assistant, Pierre Mechain.

Between 1921 and 1966, seven additional objects have been added to the catalog, with the final total being 110 objects. Many of these objects had been observed by Messier, but were not added to his catalog.

Another feature, and an important one, is that the objects in the catalog were discovered using the primitive telescopes of the day. Therefore, they are objects that can easily be seen and studied by amateur astronomers today.

The Messier Colophon, published with his catalog.

Messier’s - Colophon

The Current Catalog with 110 objects:

Messier Objects

Messier was one of the first astronomers that studied deep sky objects.

Image Source:

Image Messier Catalog: https://www.maa.clell.de/Messier/objects.html

You can read more information about The Discovery of Galaxies

Messier Objects: Nebula

Nebulae are clouds of gas and dust that reside in our Milky Way galaxy. One of the most famous nebula is the Crab Nebula.

Crab Nebula M1

Note that this is Messier object - M1, the first object in the catalog. Messier, when investigating the De La Nux comet in 1758 caused him to conclude that the object he was studying was not a comet at all. This conclusion lead him to start cataloging objects that resembled comets.

Messier Objects-Nebula

Image Source:

Messier Objects: Star Clusters

The second class of objects that Messier identified are star clusters. Star clusters are groups of stars. There are two kinds: open and globular clusters.

Open clusters have either a few stars in their local area, or they may have hundreds of new stars. New stars are usually formed within a cloud of hydrogen gas and cosmic dust. They are young stars, and the open clusters are that way because of their age and mass; there is not enough of the stars with enough mass to close the cluster to form a globular cluster.

Open Cluster M11

Open Clusters

Globular clusters have a different make up. They are packed with thousands or millions of old stars. They were formed from an earlier generation of stars and so are very old.

Globular Cluster M15 Hubble

The Globular Clusters in the Messier catalog.

Globular Clusters

See the following article: Nothing But the Facts About Globular Clusters

Messier Objects: Galaxies

The third object in the catalog are galaxies. Here Messier out did himself. He was the first astronomer to list a group of stars with their own unique characteristics. There are four types of galaxies that were in his list: spiral, lenticular, elliptical, irregular. The first kind are the spiral. A spiral galaxy usually has a flattened disk and a nuclear bulge and spiral arms emanate from it. Here are the Messier Spiral Galaxy objects.

Spiral Galaxies

M31-Andromeda Galaxy

The second type of Messier Galaxies are Lenticular

Lenticular Galaxies


A lenticular galaxy is an intermediate galaxy between spiral and elliptical galaxies. They have central bulge and disk but usually lack spiral arms and a good amount of interstellar material. Lenticular galaxies get their name from their lens-like appearance when seen edge-on. They are known as S0 galaxies in the Hubble galaxy classification scheme.

Lenticular Galaxy

The third type of galaxy in the Messier catalog is the elliptical galaxy. This is a galaxy that looks smooth, with a nondescript featureless appearance and an ellipsoidal shape.

Elliptical Galaxies

The Giant Elliptical Galaxy M87

The fourth type of galaxy is the irregular. These are galaxies that have a poorly defined structure.

Irregular Galaxies

NGC 4490 Irregular Galaxy

Note, it is easy to believe that the catalog may have been easy to construct. But to Messier they were all blobs of light and not nearly as distinguishable as the list presented today might suggest. He did not have any of the powerful equipment that modern astronomers have, or even modern amateur astronomers have today. His astronomical accomplishments are indeed noteworthy.

For a Brighthub article on galaxies see: Nothing But the Facts About Galaxies


Facts About the Messier Catalog



Messier Object Nebula


This post is part of the series: Special Astronomy Objects

In this series we look at several different astronomical objects and their composition. This will show the magnitude of size and the diversity of objects in the visible universe.

  1. Nothing But the Facts About the Messier Objects
  2. Nothing But The Facts About The Oort Cloud
  3. Nothing But The Facts About The Constellation Orion