Nautical Astronomy and Navigation Practice in the Indian Ocean (c. 1405)

Timeline

1. 1403–1405Calicut · KeralaWest Indian ports gathered Arab nautical astronomical knowledge; navigators used star tables to calculate latitude and determined ship position by the altitude of Polaris and the bearings of specific constellations, forming a navigation tradition carried both orally and in manuscripts.
2. 1405Maldives archipelago · MaldivesNavigators planned outbound and return routes according to monsoon shift patterns and lunar cycles, making astronomical calibrations at midway resupply points such as the Maldives, ensuring spice and porcelain fleets arrived at destination ports on schedule.
3. 1405–1407Sumatra and the Strait of Malacca · Strait of MalaccaIn 1405 Zheng He's first western ocean voyage set sail; the fleet used star-height navigation and the compass combined with astronomical observation, converging with existing Indian Ocean nautical astronomical traditions in Southeast Asian waters and promoting the exchange of diverse navigation knowledge.