A year ago last March, marine archeologists determined that the wreck of a ship found off the coast of Oman was the Esmerelda, one of the ships in a fleet led by Portuguese explorer Vasco da Gama in 1502. The wreck was discovered in 1998, but excavation didn’t begin until 2013, and since then, researchers have recovered more than 2,800 coins and artifacts. One of the more interesting artifacts is a bronze mariner’s astrolabe, a device used to measure the altitude of celestial bodies. The astrolabe, a primitive precursor to a sextant, is believed to be the earliest of its type ever located.

When the bronze disk was brought up from the wreck in 2016, it was suspected to be an astrolabe but was sufficiently worn so that no markings used in navigation were visible. Subsequently, laser scanning by scientists at the University of Warwick revealed etches around the edge of the disc, each separated by five degrees, confirming that it was indeed used for navigation. The Portuguese coat of arms and the personal emblem of Don Manuel I, the King of Portugal at the time of the sinking, were also found on the disk.  

In 1498, Portuguese explorer Vasco da Gama changed the course of history when he successfully sailed around the tip of Africa to reach India and then safely returned. The 24,000-mile journey opened the trade in spices and gold between India and Europe.

In 1502, Da Gama was sent back to India with an armada of 20 ships to trade for spices and to attempt to destroy the Muslim shipping that had monopolized the trade. Esmeralda was part of the fleet and was captained by da Gama’s uncle, Vicente Sodré.  Sodré was ordered by da Gama to patrol the Indian coast. Instead, Sodré sailed toward the Arabian Peninsula in search of plunder. In 1503, Esmeralda and its crew, including Sodré, were lost in a storm off the coast of present-day Oman.

Sunken treasure recovered from 500-year-old shipwreck

Thanks to Alaric Bond for contributing to this post.