Mariner’s Astrolabe Recovered From Shipwreck Is the World’s Oldest

The navigational gadget comes from the wreck of the Esmerelda, part of Vasco da Gama’s fleet that sunk off the coast of Oman in 1503

David Mearns

It may not seem as exciting as the record for the longest fingernails or largest collection of dinosaur poo, but a recent verification by Guinness World Records is a big deal for history buffs.

As Jennifer Ouellette at Ars Technica reports, a disc found on one of Vasco da Gama’s ships has been recognized as the world’s oldest mariner's astrolabe. The astrolabe in question—only one of 108 recovered by archaeologists—was located during an excavation of the wreck of the Esmerelda in 2014. As we’ve previously reported, the Esmerelda isn’t just any ship. When the wreck was initially found in 1998, it became the earliest vessel from the European Age of Exploration ever discovered.

The vessel was part of an expedition to subdue local merchants along India’s Malabar Coast undertaken by Da Gama in 1502, several years after the Portuguese explorer had successfully pioneered a trade route around the tip of Africa to India in 1497. When da Gama turned for home in early 1503, he left behind several of his 20 warships under the command of his uncles Vicente Sodré and Brás Sodré. Their instructions were to hold onto the gains the expedition had made, but the uncles had other plans. They sailed instead to the Gulf of Aden, and in a notorious series of attacks, pillaged Arab merchant ships of valuable cargo. They continued to do so until April of that year, when a massive storm grounded Brás’ ship, the São Pedro and sunk the Esmerelda with Vicente on board off Al Hallaniyah island in Oman.

Some 500 years later, when researchers came across the disc among the wreck of the Esmerelda, any navigational markings had long worn off, making it unclear what exactly they were looking at. So the wreck team invited imaging experts from the University of Warwick to travel to Muscat, Oman, in 2016 to laser scan the disk and determine if it was, indeed, an astrolabe or merely a decorative object.

In the 3D virtual model created from the scans, 18 uniform scale marks are clearly discernible, positively IDing the artifact as an astrolabe. The disk, researchers believe, was likely owned by da Gama’s cousin Vicente since it also bears the Portuguese royal coat of arms and the personal emblem of Don Manuel I. Researchers from the university’s Warwick Manufacturing Group detailed the findings in a newly published paper in The International Journal of Nautical Archaeology.

“[The Warwick Manufacturing Group’s] analysis proved beyond doubt that the disk was a mariner's astrolabe,” David Mearns, the marine scientist and wreck hunter who headed up the Esmerelda excavations, says in a press release. "This has allowed us to confidently place the Sodré astrolabe in its correct chronological position and propose it to be an important transitional instrument.”

The astrolabe, the original smartphone, if you will, has been around a long time in different forms, likely first appearing during the 2nd century A.D. For centuries the round discs, which required specialized training to master, were used for many purposes. During the European Age of Discovery, they became one of the important tools used by mariners like da Gama to calculate latitude and a simplified mariner’s astrolabe would have been aboard most European ships. The solid-disc type of astrolabe recovered from the wreck of the Esmerelda served as an interim tool, soon to be replaced by open-wheel models sometime before 1517. The gadget continued to evolve until it fell out of favor in the 1700s.

Guinness also certified that a bell recovered from the Esmerelda was the oldest-known ship’s bell. And those are unlikely to be the last finds. Mearns tells Sarah Sloat at Inverse that his team will return to the ship during a project with Oman’s Ministry of Heritage and Culture later this year.

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