Uranometria is a star atlas created by the German astronomer Johann Bayer in 1603. It was one of the first comprehensive star maps, featuring 1,564 stars and dividing the night sky into 48 constellations. Bayer introduced a system of designating stars using Greek letters, which is still in use today. The atlas was significant for its time, as it provided a detailed reference for astronomers and navigators. Uranometria helped to standardize the naming of stars and contributed to the development of modern astronomy by making celestial navigation more accessible.