Astrolabe that guided Portuguese explorers to India found

The world's earliest known marine navigation tool that may have helped legendary Portuguese explorer Vasco da Gama find his way to India has been discovered in a 14th-century shipwreck in the Indian Ocean, according to British researchers.
Researchers at the University of Warwick in the UK accurately scanned the item to within 0.1 millimetres and reproduce a high-resolution 3D model.
The tool called astrolabe is a bronze disc, which measures 17.5 centimetres in diameter, and is engraved with the Portuguese coat of arms and the personal emblem of Don Manuel I, the King of Portugal from 1495-1521.
It is believed to date from between 1495 and 1500, and was recovered from the wreck of a Portuguese explorer ship which sank during a storm in the Indian Ocean in 1503.

The boat was called the Esmeralda and was part of a fleet led by Portuguese explorer Vasco da Gama, the first person to sail directly from Europe to India.
Astrolabe was used by mariners to measure the altitude of the Sun during voyages.

The object was discovered in 2014. It had no visible markings, but was believed to be an astrolabe.
New scans showed etches around the edge of the object, each separated by five degrees - proving that it is an astrolabe.
These markings would have allowed mariners to measure the height of the Sun above the horizon at noon to determine their location so they could find their way on the high seas.

"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," said Mark Williams, from University of Warwick.