Introduction to the Messier Objects
From an amateur perspective, the Messier Catalogue contains many objects. Not only are they of different types, encompassing star clusters, galaxies and nebulae but also they are of different degrees of difficulty from those readily visible to the unaided eye to those that are tough with medium-sized amateur telescopes. Often, when asked the question “have you seen M81?”, it is more accurate to reply that you’ve seen a fuzzy patch where M81 is supposed to be. As Charles Messier predates Edwin Hubble, he was unaware of the nature of many of the objects in his catalogue. That doesn’t diminish his achievements in any way, as it is a good general list for deep sky viewing but it also succeeds in its original objective and many people (including me), resisted the temptation to go blabbing about a “new comet” after checking catalogue objects first.