Scientist of the Day - Pierre Francois Mechain

Pierre-Francois Méchain, a French astronomer, was born Aug. 16, 1744. Méchain discovered a number of deep-sky nebulous objects, including M101 (the Pinwheel Galaxy; first image), M87 (the Owl Nebula, second image), and M104 (the Sombrero Galaxy; third image). One might suppose that the "M" in M101 or M87 stands for Méchain, but in fact it stands for Charles Messier, who compiled the first catalog of nebulous objects in 1771, which he then enlarged and completed in 1781. Of the 103 objects in Messier’s 1781 list, Méchain discovered 21 of them, and if one uses the modern list of Messier objects, which now includes 110 nebulae, Méchain was the first to observe 28 of them. Messier, who was good friends with Méchain, was careful to give Méchain credit for each of the nebulae he had discovered when he published the 1781 list.

Méchain discovered the galaxy M100 on Mar. 15, 1781, and there is an interesting modern footnote relating to M100. When the Hubble Space Telescope (HST) was first launched in 1990, it recorded an image of M100, and this image was very blurry, one of the first signs that something was seriously wrong with the HST. Three years later, after the HST was repaired with some imaginative optical corrections put in place by a shuttle mission, the HST took another image of M100, and this time the gorgeous spiral was in perfect focus. The "before and after" series of M100 (fourth and fifth images) was frequently reproduced to demonstrate to Congress that their billions of dollars had not been wasted (and that the Space Shuttle was worth their investment as well).

There is a portrait of Méchain at the Paris Observatory (sixth image). Messier’s catalog of nebulae, which includes Méchain’s discoveries, was published in an almanac, the Connoissance des Temps pour l’année 1784 (1781). We have a copy of this volume, with its Messier catalog, in our History of Science Collection.

Dr. William B. Ashworth, Jr., Consultant for the History of Science, Linda Hall Library and Associate Professor, Department of History, University of Missouri-Kansas City. Comments or corrections are welcome; please direct to ashworthw@umkc.edu.