Abstract
One of the great debates in recent historiography is the consideration of the journey by Ferdinand Magellan and Juan Sebastián del Cano (1519-1522), which ended up with the first circumnavigation of the globe, as one of the most meaningful events in History. Nevertheless, the tendency to personalize the past had removed the focus from the object of analysis. One should not forget that many men participated in the heroic deed and all of them contributed to the accomplishment of the venture. That was the case of Andrés de San Martin, Royal Pilot of the ships San Antonio and Victoria. These pages are devoted to the study of this excellent cosmographer and astronomer who played a fundamental role in the historical expedition.