Crux is a modern constellation. During ancient times the stars that made up this constellation were part of Centaurus. The first mention of the constellation was in 1592 by Emerie Mollineux. The French astronomer Augustin Royer is credited with defining it as a separate constellation in 1679. Crux is the smallest constellation in the night sky, and is not visible from latitudes north of 25 degrees (Key West, Florida).