The Renaissance Florentine navigator Amerigo Vespucci made two voyages to the West, the first in 1499-1500 and the second in 1501-1502. During these expeditions, he explored over 6,000 miles of coastline and determined that the lands Columbus discovered were not islands off the continent of Asia but were part of a "new world." Using his unique system of celestial navigation, Vespucci also correctly theorized that two oceans, rather than one, lay between the west coast of Europe and the east coast of Asia. In 1507 the German geographer Martin Waldseemuller published Vespucci's accounts of his voyages and suggested that the new lands to the West be named America in honour of the man who determined that they were new continents.