US-born shipwreck hunter discovered the world’s oldest maritime astrolabe, which guided Portuguese explorers

David Mearns, a British-based shipwreck hunter was diving off the coast of Oman in 2014, and he came across a bronze disc, which was passed on to Warwick University for lab scans and analyses.

Most recently, studies from the university has confirmed of the “revealed etches” on the 17.5-centimetre wide artefact after laser scans done by Professor Mark Williams.

“It was fantastic to apply our 3D scanning technology to such an exciting project and help with the identification of such a rare and fascinating item.”  – Warwick University Professor Williams

According to Mearns, the bronze disc revealed the royal coat of arms on it and he told AFP in an interview that he knew immediately that it was “a very, very important object.”

“This is the oldest maritime astrolabe,” he said, with origins dating back to the 1496 and 1500 period, which was around 30 years earlier than the previously known oldest astrolabe.

Astrolabes – as the word suggests – is a solar navigation tool, historically used by astronomers and navigators to measure the altitude of the stars and the positioning of celestial bodies, and whether if it’s day or night according to the positioning of the sun.

Williams also found out that the “Etches was separated by five degrees intervals to calculate the height of the sun,” said AFP.

According to Mearns, the astrolabes has been used since the ancient times as a navigation tool, but the Portuguese explorer developed a version of their own for the mariners to measure the latitude of a ship at sea.

Mearns’ company began a research on the shipwreck in 1998 and started the evacuation in 2013 after his company collaborated with Oman’s culture ministry.

Mearns believes Esmeralda was a ship that sank, while Vasco da Gama was on his second voyage to India between 1502 and 1503. Being the first European to reach India by sea in 1498, he discovered the doorway to the age of colonialism and trade between Europe and Asia.

“The astrolabe carried the personal emblem of King Manuel I of Portugal, who came to the throne in October 1495.” – US-born Mearns, who has worked on shipwrecks around the world revealed the image shown on the astrolabe

The maritime astrolabe developed by the Portuguese took reference from the oldest astrolabe at that time when it was used at sea is about 1480. “The previous oldest was on a ship from 1533,” Mearns said.

The astrolabe is with Oman’s National Museum.