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Guinness World Records independently certified an astrolabe excavated on the wreck site of a Portuguese Armada ship that was part of Vasco da Gama's second voyage to India in 1502-1503 as the world's oldest, and also certified separately the ship's bell (dated 1498)) found on the same site as the oldest in the world. Credit: David Mearns
Guinness World Records independently certified an astrolabe excavated on the wreck site of a Portuguese Armada ship that was part of Vasco da Gama's second voyage to India in 1502-1503 as the world's oldest, and also certified separately the ship's bell (dated 1498)) found on the same site as the oldest in the world.
The scientific process of verifying the disk as astrolabe by laser imaging is described in an article published today by Mearns and Jason Warnett and Mark Williams of WMG at the University of Warwick in the US. International Journal of Nautical Archeology.
The Sodré astrolabe is included in the Guinness Book of World Records. It was manufactured between 1496 and 1501 and is unique in comparison to all the astrolabes of other sailors.
The astrolabes of Mariner were used for navigation at sea by the first explorers, especially Portuguese and Spanish.
They are considered the rarest and most valuable artefacts that can be found on ancient shipwrecks. There are only 104 copies in the world.
They were first used at sea during a Portuguese trip to the west coast of Africa in 1481. Then, the astrolabes were used for navigation during the most important explorations of the late fifteenth century, including those led by Bartolomeu Dias, Christopher Columbus and Vasco da. Gama.
It is the only solid disc type astrolabe whose provenance is verifiable and the only specimen decorated with a national symbol: the Royal Arms of Portugal.
Guinness World Records independently certified an astrolabe excavated on the wreck site of a Portuguese Armada ship that was part of Vasco da Gama's second voyage to India in 1502-1503 as the world's oldest, and also certified separately the ship's bell (dated 1498)) found on the same site as the oldest in the world. Credit: David Mearns
As the first verifiable sailor's astrolabe, it fills a chronological gap in the development of these iconic instruments. It is considered a transitional instrument between the classic planispheric astrolabe and the freewheel astrolabe put into service shortly before 1517.
The 175 mm diameter fine disc, weighing 344 grams, was analyzed by a WMG team that went to Muscat (Oman) in November 2016 to collect laser scans from a selection of the most important items recovered from the wreck site.
Using a 7-axis Nikon portable laser scanner, capable of collecting more than 50,000 dots per second with an accuracy of 60 microns, a 3D virtual model of the artifact was created. .
The analysis of the results revealed a series of 18 scale marks spaced at uniform intervals along the lower limb of the disc.
Further analysis carried out by WMG engineers showed that the spacing of the scale marks was equivalent to 5-degree intervals. This was crucial evidence that allowed the independent experts of Texas A & M University to list the record in their global inventory as the oldest known sailor astrolabe to date.
Professor Mark Williams of WMG, University of Warwick, comments:
Guinness World Records independently certified an astrolabe excavated on the wreck site of a Portuguese Armada ship that was part of Vasco da Gama's second voyage to India in 1502-1503 as the world's oldest, and also certified separately the ship's bell (dated 1498)) found on the same site as the oldest in the world. Credit: David Mearns and the University of Warwick
"Using this 3D scanning technology has allowed us to confirm the identity of the oldest known astrolabe, and historians and scientists can learn more about the history and navigation of ships.
Technology like this allows us to better understand how the disc would have worked in the 15th century. Using the technology normally applied in engineering projects to better understand such a valuable artifact was a real privilege. "
David Mearns of Blue Water Recoveries Ltd commented:
"Without the laser scanning work done by WMG, we would never have known that the scale marks, which were invisible to the naked eye, existed." Their analysis has conclusively proven that the The disc was a sailor astrolabe, which allowed us to place the Sodré astrolabe in its correct chronological position and proposes it as an important transitional instrument. "
Explore further:
The oldest known maritime navigation tool revealed by scanning technology
More information:
David L. Mearns et al., An ancient Portuguese sailor astrolabe from the site of the Sodré wreck, Al Hallaniyah, Oman, International Journal of Nautical Archeology (2019). DOI: 10.1111 / 1095-9270.12353
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