Astronomical Ring Artifact From the San Diego Shipwreck [Maritime Navigational Instruments]

This article features the astronomical ring from the San Diego shipwreck. This artifact is one of the navigational instruments used in the 16th century CE (Common Era) – around the time when our ancestors encountered the first circumnavigators of the world. 

The earliest sailors used recognizable landmarks to navigate the sea while staying close to the shore. When in open waters with no land sightings, they watch the direction and movement of the sun and stars to mark their position. Navigation is primarily based on the calculation of latitude and longitude. Longitude was not measured accurately until the 18th century CE, with the invention of the chronometer. With this limitation, early sailors relied heavily on tools that determine the latitude which was easily achieved by measuring the angle between the sun or star and the horizon. 

During the 16th century CE, navigation methods developed rapidly as explorers began establishing the routes of their expeditions, and determining locations of their discoveries. Significant navigational tools used in this period include the astrolabe and astronomical ring, which were both found on the San Diego shipwreck. 

Read about the San Diego’s astrolabe here: https://bit.ly/32AHqoT 

The San Diego’s astronomical ring is made of bronze (copper and tin alloy), and composed of graduated rings and a flat disc enclosed with hoops. The piece is not sufficiently well preserved, making it hard to identify the specific functions of some parts. The main function of this astronomical ring is to determine the time and day of sighting, which indicates an early approach to the determination of longitude. Similar to the astrolabe, this instrument is most likely accompanied by charts and tables to interpret the readings.

When our situation eases and your #NationalMuseumPH opens again to the public, you may visit the San Diego exhibition at the National Museum of Anthropology to see the astronomical ring and astrolabe. In the meantime, please #StaySafeStayHome and enjoy our #MuseumFromHome series.

Want to know more about the San Diego shipwreck? Download the book here for free: https://bit.ly/32lPaMg 

Saga of the San Diego Shipwreck

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Credits:

Text and poster by the Maritime and Underwater Cultural Heritage Division

©National Museum of the Philippines (2021)