[Charles Messier]
Last Updated 08.01.2009
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[Chuck]Charles Messier came to Paris in 1751 at the age of 21. He was hired by the astronomer Joseph Delisle as a draftsman, and as a recorder of astronomical observations. By 1754 he was also an accomplished observer, and at about that time he took a position at the Marine Observatory in Paris as a clerk.

This was the time when astronomers were anticipating the first predicted arrival of Halley's Comet. Delisle had made a map of the routes by which the comet could approach to arrive at its predicted perihelion, and Messier, his observing assistant, thus had the inside track in discovering (or rediscovering) it. He searched for 18 months, but in vain - Delisle had in fact miscalculated.

Meanwhile on Christmas night, 1758, a German farmer named Johann Georg Palitzsch discovered the comet. A month later, Messier did as well, having not heard of Palitzsch's success (no Internet). Delisle would not let Messier announce his discovery, until after Palitzsch's news finally reached Paris. This loss of 'credit' may well have forged Messier's determination to discover more comets.

After Delisle's retirement, Messier continued observing from the Hotel de Cluny. He discovered the comet of 1764, and (with the naked-eye) saw the comet of 1766. Over the next 15 years, nearly all comet discoveries were made by Messier. One perhaps apocryphal story relates that while at Messier sat at his wife's deathbed, a rival astronomer discovered a comet. When a friend consoled him on his loss, he said, "Alas! I have discovered a dozen of them; Montagne had to take away the 13th!" Only then did he realize that his friend was talking about the loss of his wife!

[Hotel de Cluny]
Hotel de Cluny as it appeared in Messier's day.

Messier did more than look for comets - he observed occultations, transits, eclipses, and sunspots. He was no theoretician, however; for all his comet discoveries, his assistants reduced his observations to the orbital elements.

In 1758, he wrote, "When the comet of 1758 was between the horns of Taurus, I discovered above the southern horn and a short distance from the star Zeta Tauri a whitish light, extended in the form of a candle light, which contained no stars. This light was a little like that of a comet I had observed before; however, it was a little too bright, too white, and top elongated to be a comet, which had always appeared to me almost round,..." It was the Crab nebula in Taurus - M1, and was duly plotted on the chart of the comet. The next object, the globular cluster in Aquarius, was observed in 1760.

By 1764, Messier had accumulated a number of such 'false comets' and began to make a list of them. In seven months Messier cataloged 40 objects - including the Hercules cluster (M13), the Omega (M17) and Trifid (M20) nebulas, the Dumbbell planetary nebula (M27), and the Andromeda galaxy (M31). To make his list as complete as possible, he added objects from previous catalogs by Edmund Halley (only five objects), William Derham, and Lacaille.

In 1765, he discovered the open cluster near Sirius (M41). In 1769, he also determined the positions of the previously-known Orion nebula (M42, M43), the Pleiades (M45), and Praesepe (the Beehive) to bring his list to 45 in time for his admission to the Academie Royale des Sciences in 1770, where it was published as Catalogue des Nebuleuses et des amas d'Etoiles, que l'on decouvre parmi les Etoiles fixes, sur l'horizon de Paris in 1771. Three nights after presenting this memoir, he recorded the positions of four more clusters!

In the years following, a few more objects were discovered in connection with comet searches. A break took place in 1779, when the comet of that year passed across the Coma - Virgo region, leading to the first sightings of the brighter galaxies of that area. The next year, he observed the M65 and M66 galaxies in Leo, to bring his list to 68 in time for the publication of the French almanac, Connaissance des Temps.

A few of the Messier objects have been mysterious or controversial, although it seems that most of the problems have been worked out by now. For example, the description given by Messier of M47:
7h 44m 16s, -1 16' 42". Cluster of stars a short distance from the preceding, (M46 cluster) the stars are brighter; the middle of the cluster was compared with the same star, 2 Navis. The cluster contains no nebulosity.
Messier's descriptions of his telescopes are rather unsatisfying; he usually says something like "easily visible in a telescope of two feet" (focal length). In fact, his favorite telescope was actually a Gregorian reflector with a focal length of 32 inches and an aperture of 7 1/2 inches. The mirrors were of polished speculum metal, which would mean a light-gathering power about equivalent to a three-inch modern aluminized glass mirror. (I think we should do our Messier Marathon using 80 mm telescopes!)

By this time, Messier had a new rival, Pierre Mechain, an astronomer at the naval map archives in Paris, who was 14 years his junior. In 1781, Mechain discovered two new comets, and in the course of his searches also found 32 new nebulous objects, which he communicated to Messier. Messier would then observe the new objects and add them to his list in the order he (Messier) observed them. Mechain discovered many new Virgo cluster galaxies. In light of Messier's previous jealousy about comet discoveries, it is surprising that the historical record betrays no such jealousy towards Mechain.

In April of 1781 the list stood at 100, with 24 of these having been referred from Mechain. That November, Messier had a serious fall into an icehouse, breaking his arm, leg, and two ribs. Messier did not resume observing until a year after. In 1784, the list was republished, including three new objects from Mechain that Messier had not had time to verify. M102 is another 'mystery' object, although it turns out that Mechain sent a letter to Bernoulli stating that it was actually a mistake, being identical to M101. (In the modern list, M102 is assigned to NGC 5866, which matches Mechain's position and description.) In this letter, Mechain also describes six new objects, bringing the list to 107 (discounting 102). In 1787, the list was republished in its final form during Messier's lifetime, this time edited by Mechain. The printed description of the Owl Nebula (M97) makes reference to three more undescribed objects in the vicinity. This, together with marginal notes on a copy of the 1787 list in Messier's hand, and a few other objects known to have been observed by Messier has been used to extend the list to the present 110 objects.

By 1790, revolution and economic turmoil brought trying times for Messier, who lost his navy pension and salary. In spite of circumstances, he managed to discover another comet in 1793. As the political situation stabilized, Messier was elected to the new Academy of Sciences, and received the Legion of Honor from Napoleon. He lived to the age of 86, dying on April 12, 1817.

Looking back on his interest in nebulae, Messier wrote in the Connaissance des Temps for 1801:

What caused me to undertake the catalogue was the nebula I discovered above the southern horn of Taurus on September 12, 1758, while observing the comet of that year.... This nebula had such a resemblance to a comet, in its form and brightness, that I endeavored to find others, so that astronomers would not confuse these same nebulae with comets just beginning to shine. I observed further with the proper refractors for the search of comets, and this is the purpose I had in forming the catalogue. After me, the celebrated Herschel published a catalogue of 2,000 which he has observed. This unveiling of the sky, made with instruments of great aperture, does not help in a perusal of the sky for faint comets. Thus my object is different from his, as I only need nebulae visible in a telescope of two feet [length]. Since the publication of my catalogue I have observed still others; I will publish them in the future, according to the order of right ascension, for the purpose of making them more easy to recognize, and for those searching for comets to remain in less uncertainty.

(This article is largely abstracted from "Messier and His Catalogue" by Owen Gingerich, to which the interested reader is referred for further details.)

Article courtesy of Mark Miller

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