Toscanelli, Paolo (1397–1482)

An Italian physician, astronomer, mapmaker, and mathematician who is best known for creating a map of the world that may have been used by Christopher Columbus in planning his voyage to the East Indies. Born in Florence, he was the son of a doctor, Dominic Toscanelli. He studied mathematics with Giovanni dell'Abacco in Florence and attended the University of Padua, earning the title of doctor of medicine in 1424. He returned to Florence and earned a reputation as a leading mathematician and astronomer, considered by many people to be the most brilliant scientist of his day.

A skilled astronomical observer, Toscanelli observed and measured the orbits of comets, including the occurrence of Halley's Comet in 1456. In the cathedral of Florence he designed a gnomon, a slab of marble placed high in the left transept of the church that cast a shadow of the sun, allowing an observer to determine noon and measure the occurrence of the winter and summer solstices. From his studies of ancient writers, including Ptolemy, and his conversations with travelers and explorers, Toscanelli created a map of the world that was sent to the king of Portugal in 1474, and explained the possibility of sailing west, rather than around Africa and through the Indian Ocean, to reach the East Indies. The scheme became known to Christopher Columbus, who corresponded with Toscanelli and who carried a copy of Toscanelli's map and letter with him on his first voyage. Toscanelli miscalculated the size of the globe, however, believing Europe and Asia to cover much more of the earth's surface than they actually do. This misconception convinced Columbus that he had actually reached Asia in 1492, whereas his fleet had in fact only sailed as far as the eastern islands of the Caribbean Sea.

See Also: Columbus, Christopher; exploration