Final answer:
Amerigo Vespucci was the first explorer to realize that South America was a separate continent from Asia, leading to the naming of America by mapmaker Martin Waldseemuller. Magellan's circumnavigation later confirmed the vastness of this New World.
Step-by-step explanation:
Who First Realized That South America Was Not Part of Asia?
The first explorer to understand that South America was a new continent, separate from Asia, was Amerigo Vespucci. Unlike Christopher Columbus, who believed until his death that he had reached Asia, Vespucci, sailing for the Portuguese crown between 1499 and 1502, recognized that the lands he explored along the South American coastline were part of a New World. His observations and the subsequent publication of his accounts led to a shift in thinking about these newly discovered territories among Europeans.
German mapmaker Martin Waldseemuller was influenced by Vespucci's accounts and labeled the new continent America on his world map in 1507, a name which permanently entered cartography and common usage. Interestingly, it wasn’t until Ferdinand Magellan's expedition that further proof was provided about the distinctness of the continents, after his fleet's circumnavigation confirmed the vastness of the Pacific and the separate landmasses.
The early explorers, like Columbus, aimed to discover new trade routes to Asia but instead opened the doors to the immense wealth and diverse cultures of the Americas, leading to significant colonization and exploitation of these new lands.