Some historians have claimed that the Portuguese had already performed fairly accurate calculations concerning the size of the world and therefore knew that sailing west to reach the Indies would require a far longer journey than navigating to the east.
Nogle historikere har hævdet, at portugiserne allerede havde udført temmelig præcise beregninger af, hvor stor jorden var, og derfor vidste, at det ville kræve en meget længere rejse at nå til Indien ved at sejle mod vest end ved at sejle mod øst; men dette spørgsmål er stadig omstridt.