The Stan Cocking Memorial Lecture: Comets, Ferrets and Nebulae: Charles Messier and 18th Century Astronomy presented by Dr. A Chapman.
For those of you who are interested in the life and achievements of Charles Messier (1730-1817), you can easily do a search on the www, but you know that a talk on the subject by our local luminary, Dr Allan Chapman, is not going to be run of the mill.
When Charles Messier appeared on the scene, comets were still very much mysterious and misunderstood. They were monitored by Tycho Brahe, who had managed to observe some quite spectacular comets and supernovae. He finally had to admit that they were further than the Moon, and this challenged the whole of Greek physics.
Robert Hooke in 1664 observed that the comet had internal structure and produced its own light, so could not be reflected sunlight. But why did its tail get so much brighter near the Sun? Was it a braking effect? Was it disintegrating? Could a comet go behind the Sun and come out from the other side? Johannes Hevelius did lots of drawings of comets and the comet of 1682 was observed all across Europe. Edmond Halley worked out an orbit, which indicated it would come back in 1758. So it did, and this famous fellow that bears his name has been back a few times since.
So, when a 14 year old Charles Messier saw a six-tailed comet in 1744 he became hooked. He was already interested in Astronomy and by the age of 21 he was receiving a privileged education as a student of Joseph Delisle, who supplied all things astronomical to the French Navy and the palace of Versailles. He was based at the Hotel de Cluny in Paris and was lucky to be funded by the French aristocracy, who were happy to fund all his comet hunting as well as other astronomical phenomena, such as transits and other experiments to work out the shape of the Earth. (In the UK there was no public money being spent on astronomy at the time, part from a little at Greenwich.)
So, Messier was employed to look for comets, but was finding himself thwarted when he would be observing some nebula over several days and realised it was not a comet. He began making a list of them in order to save wasting time on them, and started his final list with the Crab nebula in Taurus.
The rest is history. Dr Chapman says Halley published a list of six objects in 1716, but I don’t know which ones they were. Messier never observed any comet on its subsequent return.
If you want to read his own descriptions of the objects in his catalogue, including those of his contemporary Pierre Mechain, they are copied from originals and are in the 1978 observer’s handbook called ‘The Messier Album’, by John H. Mallas and Evered Kreimer. There is also a lengthy description of Messier’s doings, including his very unfortunate fall through an icehouse door in November 1781 and fell 25 feet down onto the ice.
Messier was called the comet ferret by King Louis xv. He discovered 13 comets and 8 are co-discoveries.