Portuguese exploration of Africa and Asia , Columbus ' voyage to the Americas ( 1492 ) and finally Ferdinand Magellan 's circumnavigation of the earth ( 1519-21 ) provided the final , practical proofs for the global shape of the earth . Portuguese exploration of Africa and Asia , Columbus 's voyage to the Americas ( 1492 ) and finally Ferdinand Magellan 's circumnavigation of the Earth ( 1519 â `` 21 ) provided the final , practical proofs for the global shape of the Earth .