1771

Messier Catalog

Charles Messier (1730–1817), Pierre Méchain (1744–1804)

Frenchman Charles Messier had a lifelong interest in astronomy that was stimulated by witnessing exciting celestial events when he was a child—such as the great comet of 1744 and the solar eclipse of 1748. His passion for observing led him to take a job in Paris working as a depot clerk for the official astronomer of the French navy, a job that entailed the use of an observatory on the roof of the Hôtel de Cluny.

Messier had ample time to observe, and a good dark-sky observing location in pre–Industrial Revolution Paris. His early passion appears to have been comet hunting. He was among the first astronomers to verify the predicted return of Halley’s comet in 1758–1759; during the search he discovered another comet as well as a comet-like smudge of light in the constellation Taurus. Unlike a comet, however, this smudge didn’t move relative to the stars. He made a note of it.

As he continued hunting comets over the next decade, he continued encountering one fuzzy, cloud-like nebula after another, giving each a designation of the letter M followed by a number. Some, like M22, which had been discovered in 1665, he could barely resolve as a circular cluster of huge numbers of closely packed stars (later called globular clusters); others, like M31, had an elongated shape and had been previously recognized as the great nebula in Andromeda. Many were objects that Messier himself was the first person to discover and describe. He had collected so many that by 1771 he had amassed a collection of 45 objects, which he published as his “Catalogue des nébuleuses et des amas d’étoiles” (“Catalog of Nebulae and Clusters of Stars”) in the journal of the French Academy of Sciences. By 1781 he and his colleague Pierre Méchain, a future director of the Paris Observatory, had amassed even more; their final catalog contained 103 objects.

Twentieth-century astronomers discovered seven more objects that Messier and Méchain observed after 1781, bringing the total number of Messier objects—now recognized as star clusters, planetary nebulae, molecular clouds, and galaxies—to its modern value of 110. Some amateur astronomers and astronomy clubs try to observe all 110 objects during springtime “Messier marathons.” Who knows—such events might help inspire another child’s passion for astronomy.

A compilation of all 110 official Messier objects, gathered from observations by the Students for the Exploration and Development of Space (SEDS) and the Paris Observatory at Meudon.