Summary: The name Messier is synonymous with the deep sky. The man himself was an unfaltering 18 th century French astronomer who changed the course of astronomy with his catalogue of " Star Clusters and nebulae ", as well as the discovery of over 20 comets. Messier's revolution in the observation of galaxies, nebulae and star clusters is significant enough in the history of astrobiology. But what did Charles Messier make of the alien life debate?
Messier was born in Badonviller in 1730. He grew up in a fairly affluent household until, at the age of 11, young Charles lost his father. Messier's formal education ceased, and his life was utterly changed. Charles had already developed a love for learning and a passion for astronomy. Now, under the tutelage of his brother Hyacinthe , Messier received a home schooling that would serve him well in later life.
By the age of 21, Messier had secured a position at the Paris observatory under the secretary of the Navy, Nicolas DeLisle . Messier embraced this newfound opportunity with enthusiasm and zeal. By 1757 he had made his crucial breakthrough while tracking the much-awaited return of Halley's comet. Although the comet caused a sensation, it was a small nebula in Taurus that captured Messier's attention. The discovery made up his mind. He would compile a catalogue of nebulous objects "to avoid whilst looking for comets" . By 1771 his work was complete, and Messier's pioneering work of the universe at large earned him election to the French Royal Academy of Sciences.
Now Messier's life began to overlap with many other great scientific figures of the time. French astronomers Jerome Lalande and Jacques Dominique, comte de Cassini , mathematician Pierre Simon Laplace , the great philosopher Voltaire, German astronomer William Herschel, and director of the Berlin Observatory, Johann Elert Bode. These workers in the field and a host of others stand out like a glittering constellation of science and society in 18 th century Paris and Europe. What influence did their speculations on life in the universe have upon such a humble figure as Messier? Membership of the Academy opened up a world of philosophical discussion that was both profound and immediate. Potentially overwhelmed by the influence of his contemporaries, Messier stuck to what he knew best - reporting his observations in astronomy. Only rarely did he draw philosophical conclusions. Messier preferred to let others use his data to speculate on the nature of the heavens.
But one debate could not be avoided - the question of the plurality of inhabited worlds. The idea of life on other planets was not new. The genesis of such speculation went all the way back to the Greek atomists of 6 th century BC, Leucippus and Democritus. And in France the publication in 1686 of Bernard le Bovier de Fontenelle's Conversations on the Plurality of Worlds had caused a massive stir. Messier had a direct link to this formative work on the science communication of astrobiology. He was a close personal friend of Jerome de Lalande , the editor of the 5 th edition of Conversations . No doubt Messier would have been party to the heated debates on alien life, and would have undoubtedly have enthusiastically joined in the speculations of Lalande and their colleagues. Indeed Lalande's Traite d'astronomie (1792) contains a section on the plurality of worlds, in which he suggests, "Imagination pierces beyond the telescope; it sees a new multitude of worlds infinitely larger ", a direct reference to the newly discovered deep sky of Messier's groundbreaking work beyond the solar system.
It was a period of great change. The old feudal world had come crashing down before the new social forces of the Scientific Revolution. And the new alien universe unveiled by the telescope found its chief theorists in Isaac Newton and René Descartes. Their materialist interpretation of a 'clockwork' universe was to be found everywhere. And early notions of astrobiology did not escape the reach of the New Philosophy. The religious consequences of pluralism were discussed quite openly in Traite de l'infiniti Cree by the priest Jean Terrasson , a train of thought that any good catholic, Messier included, would have taken seriously. Voltaire's Micromegas was greatly celebrated for its imaginative commentary on aspects of western culture by a being from a planet circling the star Sirius and his companion from the planet Saturn.
Indeed, French science and culture of the time teamed with the idea of alien life. Compte de Buffon had published his Histoire Naturelle in 1749, Emmanuel Swedenborg had considered Earths in our Solar System in 1750, and Marie-Anne de Roumier -Robert's 1765 book, Voyage de Milord Céton dans les Sept Planètes ( Lord Seton's Voyage Among the Seven Planets ), had kept the speculation of life elsewhere alive in the true tradition of Fontenelle himself.
Messier was a creature of the culture in which he swam. He was a member of the Academy of Harlem in the Netherlands, a fellow of the Royal Society in England, an Academician of Auxerre and a member of the Institute of Bologne . The possibility of life elsewhere in the universe was on the science agenda of institutions throughout Europe. Indeed, Messier was also a foreign member of the Literary Society of Sweden, where Swedenborg's hypotheses were hotly debated. And Messier was undoubtedly aware of the solar nebulae hypothesis of Laplace , who forged a pluralist approach in his Exposition du Systeme du Monde of 1796. Here was Messier's deep sky writ large for a universe seeded with life - nebulae as new solar systems in the making.
And Messier added to these astrobiological speculations with his own discoveries. Though he carefully and dispassionately reported observing strange 'lights' in the rings of Saturn from 1774 onward, others were keen to let fly the imagination. Charles Cros later ( Etudes sur les moyens de communication avec les planetes , 1869) put forward the theory that the 'lights' seen by Messier were attempts at extraterrestrial contact by aliens. Even when dead, it seems, Messier could not avoid the lively speculation his discoveries created.
Professor Mark Brake and Martin Griffiths