Who are the continents of the western hemisphere named for?

Italian cartographer and explorer Amerigo Vespuci. He was the first to identify South America as a continent. Ask yourself, how would he be able to do that without having to sail all the way around it? He figured it out by discovering the mouth of the Amazon river. He estimated that a river of that size and volume had to be collecting rain from a watershed the size of Europe. Ergo, he was sailing off a continent, rather than just another large island.