The Messier Catalogue
Charles Messier
Charles Messier (June 26, 1730 – April 12, 1817) was a French astronomer who in
1774 published a catalogue of 45 deep sky objects such as nebulae and star clusters.
The purpose of the catalogue was to help comet hunters (like himself) and other
astronomical observers to distinguish between permanent and transient objects in
the sky.
Messier was born in Badonviller in the Lorraine region of France, the 10th of 12
children of catchpole Nicolas Messier and Francoise b. Grandblaise. Six of his brothers
and sisters died young, and in 1741, his father died. Charles' interest in astronomy
was stimulated by the appearance of a great six-tailed comet in 1744 and by an annular
solar eclipse visible from his hometown on July 25, 1748.
In 1751 he entered the employ of Joseph Nicolas Delisle, the astronomer of the French
Navy, who instructed him to keep careful records of his observations. Messier's
first documented observation was that of the Mercury transit of May 6, 1753.
The Messier Catalogue
The first version of Messier's catalogue contained 45 objects and was published
in 1774 in the journal of the French Academy of Sciences in Paris. By the time the
final version of the catalogue was published in 1781, the list of Messier objects
had grown to 103. On several different occasions between 1921 and 1966, astronomers
and historians discovered evidence of another seven deep-sky objects that were observed
either by Messier or his friend and assistant Pierre Mechain shortly after the final
version was published. These seven objects, M104 to M110, are accepted by many astronomers
as "official" Messier objects. The objects' designations, from M1 to M110, are still
in use by professional and amateur astronomers today.
The catalogue is not scientifically organised by object type or by location (as
the later New General Catalogue would be). Nonetheless, the Messier catalog comprises
examples of every known deep sky object, including galaxies, planetary nebulae,
open clusters, and globular clusters. Because these objects were accessible to the
relatively small aperture telescope (approximately 102 mm, or 4 inches) used by
Messier to study the sky, they are among the most spectacular deep sky objects available
to modern amateur astronomers using much better equipment.
Furthermore, almost all of the Messier objects are among the closest to our planet
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. Professional astronomers still refer to objects by their Messier designation,
and in amateur astronomy they are among the most frequently visited deep sky objects.
Because Messier lived and did his astronomical work in France in the Northern Hemisphere,
the list he compiled contains only objects from the north celestial pole to a celestial
latitude of about –35°. Many impressive Southern objects, such as the Large and
Small Magellanic Clouds are excluded from the list. Because all of the Messier objects
are visible with binoculars or small telescopes (under favourable conditions), they
are popular viewing objects for amateur astronomers. In early spring, astronomers
sometimes gather for "Messier marathons", when all of the objects can be viewed
over a single night.
The Messier crater on the Moon and the asteroid 7359 Messier were also named in
his honour.