Pierre Mechain: Messier's Rival Comet-Hunter
August 2020 :
It's really nice to have a comet in the sky right now, the brightest in over two decades. With NEOWISE still visible, perhaps we should think of one of the major comet discoverers of the 18th century: Messier? No, Pierre Mechain.
Born August 16, 1744, Mechain, despite a lack of schooling, became a major force in coastline surveying; however, when he met Charles Messier, he added the observations of deep-sky objects, and, with Messier, began to observe comets.
In his lifetime, Mechain is believed to have discovered, or co-discovered, 11 comets. Like Messier, he was aware of the number of deep-sky objects that could be mistaken for comets, and documented them. All together, it is believed he discovered at least two dozen objects, and could be credited with several others.
Even though Mechain is believed to have discovered fewer comets than Messier, it was well-known at the time their comet counts were, for each, a matter of pride. It is said that one time Messier, so absorbed in observing the sky, fell into a hole and broke his leg. His major concern was that Mechain could then surpass him in comet counts.
Mechain, although known more for his comet discoveries, his major work was mapping the arc of the Earth's surface, in order to determine a measurement which would become the standard of the metric system. Unfortunately, while traveling to Spain, he contracted yellow fever, and never was able to continue, and confirm, his measurements. Although during his lifetime, it was feared his results were fairly large, satellite measurements in the 20th century seem to have determined that his error was about the measure of a human hair.
