Charting the galaxies in the sky has come a long way since the 18th century, when Charles Messier first included 40 nearby galaxies in his catalog of celestial objects. The New General Catalogue of Nebulae and Clusters of Stars of 1888 listed more than 6,000 such galaxies, while the Third Reference Catalog of Bright Galaxies, published in 1991, lists more than 23,000.