“It takes considerable knowledge just to realize the extent of your own ignorance.” –Thomas Sowell
Every object of the 110 in the Messier Catalogue tells its own unique story, but not every object is a true astronomical object on its own! Along with two groupings of stars — a double star (M40) and a quadruple star (M73) — there’s also a very special object that’s neither a star cluster nor a chance grouping: the Sagittarius Star Cloud!
What you’re actually seeing is a hole in the “dust” of the Milky Way’s plane, enabling us to see more than 10,000 light-years, all the way to the closest spiral arm to us. That little window opens up, by angular size, the largest Messier object of them all!
Go read the whole story, and enjoy the amazing images that come with it!