Mar 18, 2019 14:00:00

Latest laser scan revealed that the mysterious disk recovered from the sunken ship was the world's oldest navigational survey instrument

Vasco da Gama , a Portuguese explorer active in the 15th century, is known as the first person to establish a route from Europe to the South African coast to India. A mysterious disk recovered from the sunken ship, one of the fleets led by Da Gama, was found by the latest laser scan survey to be the world's oldest navigational survey instrument.

An Early Portuguese Mariner's Astrolabe from the Sodré Wreck-site, Al Hallaniyah, Oman-Mearns--International Journal of Nautical Archaeology-Wiley Online Library
https://onlinelibrary.wiley.com/doi/full/10.1111/1095-9270.12353

Earliest Known Mariner's Astrolabe research published today to go in Guinness Book of Records | EurekAlert! Science News
https://www.eurekalert.org/pub_releases/201-03/uow-ekm031519.php

A sinking ship was confirmed off the coast of Oman in 1998, and as a result of the investigation, 'The Esmeralda, which is said to have sunk when it returned to Portugal in 1503, was one of the fleets led by Da Gama. There is a high possibility, 'said Oman's Ministry of Heritage and Culture. It is said that the sinker of the king of the king's royal coat of arms and the coat of arms of Manuel I were displayed to show that it was a king's fleet ship.

The following picture shows the disk that was among the approximately 2,800 artifacts recovered from this sunken ship. The appearance when a was found, the left of b is the front, the right is the back. c is a sketch of the surface and d is an X-ray photo. You can see that the surface seems to have a design that seems to be the coat of arms of the Portuguese royal family, but nothing is drawn on the back side in particular, and it was unclear what application it was used for.

However, when a research team

at the University of Warwick , led by archeologist Mark Williams, scanned the artifacts recovered from the wreck in 2016, it turned out that the disk was the surveying instrument, the astrolabe . Astrolabe is a device used by astrologers, astronomers, navigators and surveyors to survey the height of the sun, moon and stars. The Astrolabe, believed to have been invented in the Islamic world, was transmitted to Europe in the 11th century, and is believed to have been widely used until the 6th century was invented in the 18th century.

The image below shows the laser scan of the back of the disc. It was found that a scale was engraved around the disc at a constant angle of 5 degrees in the upper right portion of the back of the disc. It is believed that the navigators used this disc to measure the sun's height at noon to know the exact position of the ship on the sea. The Astrolabe recovered from the sunken ship was made between 1496 and 1501, and is the oldest of the 108 astronauts for navigation that have been found so far.

Astrolabe is to be applied to the Guinness Book of the World with the bells recovered from the ship as 'the oldest navigational survey instrument in the world'. The shipwreck hunter David Myrns, who was involved in the survey, said, “With the Laser Scan by the University of Warwick, I could not notice the existence of invisible scale marks. It proved to be an astrolabe for voyage, which, even in light of previous studies, was of the correct age and considered to be an important means for voyage. '