A Rare Mariner’s Astrolabe Dating Back To 1503 Has Just Been Listed As The World’s Oldest Navigational Tool

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A mariner’s astrolabe that dates back to between 1496 and 1501, which was on a ship that sank in 1503, has just been listed as the world’s oldest astrolabe by Guinness World Records.

As Live Science reports, the ancient mariner’s astrolabe was lost with the ship it was on in 1503, very close to the island of Al-Ḥallānīyah, and the recovered navigational tool is now one of just 104 remaining astrolabes that have been recovered and saved from the ravages of time.

After this device was analyzed in 2017, David Mearns, an oceanographer at Blue Water Recovery, noted the following.

“It is a great privilege to find something so rare, something so historically important. It was like nothing else we had seen,” Mearns said.

Astrolabes, like the one found on the ship which sank in 1503, were highly important navigational tools which mariners once used to accurately gauge the current altitude of the stars and the sun. By doing this, the latitude of the ship could then be properly ascertained. As such, these devices were crucial tools for journeys at sea.

This particular astrolabe was first dredged from the Arabian Sea in 2014, after sinking with a ship that was once under the control of Vicente Sodré, the vessel’s Portuguese commander, who is today remembered for being the uncle of the intrepid explorer known as Vasco da Gama.

The 1503 astrolabe was originally discovered under 1.3 feet of sand, very close to where the ship had originally gone down in the Arabian Sea, and was found to be 6.9 inches in diameter.


Decorating the navigational tool was both an armillary sphere as well as a lavish Portuguese coat of arms, and after analyzing the device, scientists learned that it was constructed mainly out of copper, with smaller amounts of tin, lead, and zinc.

Because this astrolabe had been in saltwater for over five centuries, the vast majority of its markings had been obliterated. However, scientists at the University of Warwick in England were able to analyze its decorations by utilizing laser scanning, which allowed them to find extremely small etchings upon the device which normally couldn’t be seen with the naked eye.

Scientists have now determined that there were once 18 tiny markings on the far right side of the astrolabe which would have originally been used to ascertain the exact angle of the stars and sun.

The latest research into this astrolabe, which has just been listed as the world’s oldest navigational tool by Guinness World records, has been published in The International Journal of Nautical Archaeology.