Image copyright Philip Koch Image caption The instrument was once used by mariners to measure the altitude of the Sun during their voyages 
 
 An artefact excavated from a shipwreck off the coast of Oman has been found to be the oldest known example of a type of navigational tool. 
 
 Marine archaeologists say the object is an astrolabe, an instrument once used by mariners to measure the altitude of the Sun during their voyages. 
 
 It is believed to date from between 1495 and 1500. 
 
 The item was recovered from a Portuguese explorer 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. 
 
 Media playback is unsupported on your device Media caption Divers uncover 500-year-old Vasco da Gama fleet treasure 
 
 David Mearns, from Blue Water Recovery, who led the excavation and is the author of The Shipwreck Hunter, told the BBC: "It's a great privilege to find something so rare, something so historically important, something that will be studied by the archaeological community and fills in a gap." 
 
 The astrolabe was discovered by Mr Mearns in 2014, and was one of nearly 3,000 artefacts recovered during a series of dives. 
 
 The bronze disc measures 17.5cm in diameter and is less than 2mm thick. 
 
 "It was like nothing else we had seen and I immediately knew it was something very important because you could see it had these two emblems on it," said Mr Mearns. 
 
 "One I recognised immediately as a Portuguese coat of arms... and another which we later discovered was the personal emblem of Don Manuel I, the King of Portugal at the time." 
 
 The excavation team believed the object was an astrolabe, but they could not see any navigational markings on it. 
 
 However, a later analysis uncovered its hidden details. 
 
 Laser scanning work carried out by scientists at the University of Warwick revealed etches around the edge of the disc, each separated by five degrees. 
 
 Image caption The University of Warwick used laser scans to uncover etches on the astrolabe, which helped navigators work out the height of the sun 
 
 This 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. 
 
 Mariners' astrolabes are relatively rare, and this is only the 108th to be confirmed catalogued. It is also the earliest known example by several decades. 
 
 Mr Mearns said: "We know it had to have been made before 1502, because that's when the ship left Lisbon and Dom Manuel didn't become King until 1495, and this astrolabe wouldn't have carried the emblem of the King unless he was King. 
 
 "I believe it's probably fair to say it dates roughly to between 1495 to 1500. Exactly what year we don't know - but it is in that narrow period." 
 
 He added: "It rolls back this history by at least 30 years - it adds to evolution, it adds to the history, and hopefully astrolabes from this period can be found." 
 
 Follow Rebecca Morelle on Twitter. ||||| Details on earliest known marine navigation tool revealed by scanning technology at WMG, University of Warwick 
 
 Late fifteenth-century astrolabe - used by mariners to measure the altitude of the sun – recovered from Portuguese explorer ship which sank in 1503 
 
 - used by mariners to measure the altitude of the sun – recovered from Portuguese explorer ship which sank in 1503 Pioneering scanning analysis and 3D imaging revealed invisible navigational markings, proving the identity of the object 
 
 Details of the earliest known marine navigation tool, discovered in a shipwreck, have been revealed thanks to state-of-the-art scanning technology at WMG, University of Warwick. 
 
 Professor Mark Williams from WMG was tasked with scanning the artefact – an astrolabe from the late fifteenth century, used by mariners to measure the altitude of the sun during voyages – which was excavated in 2014 by Blue Water Recovery. 
 
 When the team found the object, no markings were visible – they believed it was an astrolabe, but they could not see any navigational markings on it. 
 
 They then approached Professor Williams, who conducts pioneering scanning analyses in his laboratory at WMG, to reveal the artefact’s invisible details. 
 
 The 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. 
 
 
 
 
 
 The technology was able to accurately scan the item to within 0.1mm and reproduce a high-resolution 3D model. 
 
 Professor Mark Williams commented: 
 
 “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. 
 
 “Usually we are working on engineering-related challenges, so to be able to take our expertise and transfer that to something totally different and so historically significant was a really interesting opportunity.” 
 
 The astrolabe is a bronze disc, which measures 17.5cm 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. 
 
 David Mearns, from Blue Water Recovery, who led the excavation, commented: 
 
 "It's a great privilege to find something so rare, something so historically important, something that will be studied by the archaeological community and fills in a gap. 
 
 “It was like nothing else we had seen […] it adds to the history, and hopefully astrolabes from this period can be found." 
 
 To read the BBC article about this, click here. 
 
 To hear about this on BBC Radio 4's Today Programme, click here (listen from 2:24:26) 
 
 ﻿Image 1: Scan of the astrolabe artefact - credit University of Warwick (click for high res) 
 
 Image 2: Scan of the astrolabe artefact, revealing the etches - credit University of Warwick (click for high res) 
 
 Image 3: Scanning the artefact in the laboratory at WMG - credit University of Warwick (click for high res) 
 
 24 October 2017 ||||| Left By Explorer's Armada, Shipwreck Yields 'Earliest Known' Marine Astrolabe 
 
 By early 1503, most of Vasco da Gama's armada was returning home to Portugal after his second voyage to the Indian coast. The explorer, now roughly five years removed from discovering a direct sea route from Europe to India, left behind several ships to patrol (and pillage) the waters near modern-day Oman — but the winds eventually rose and smashed several of the remaining ships in raging storms. 
 
 Now, more than 500 years later, the sunken ruins of one of those ships have yielded a surprising discovery: the world's "earliest known" marine astrolabe, according to researchers at the University of Warwick. They say the navigation tool, which sailors would use to reckon time by gauging the position of the sun and stars, dates to between 1495 and 1500. 
 
 The instrument was one of more than 2,800 artifacts recovered from the Esmeralda, which has been under excavation since 2013. When Blue Water Recoveries first pulled it from the depths in 2014, David Mearns, the group's expedition leader, said he and his team suspected the 7-inch bronze disc could be an astrolabe. 
 
 "It was like nothing else we had seen and I immediately knew it was something very important because you could see it had these two emblems on it," he told the BBC. "One I recognised immediately as a Portuguese coat of arms... and another which we later discovered was the personal emblem of Don Manuel I, the King of Portugal at the time." 
 
 But the centuries-old instrument no longer betrayed any discernible navigational markings. Mearns and his colleagues needed some help to find them. 
 
 Enter Mark Williams, a professor at Warwick who used "pioneering analysis and 3D imaging" to reveal hidden "etches around the edge of the object, each separated by five degrees." These markings would help sailors of the day judge a celestial body's position with relation to the equator and their own position on the water — and, for researchers of today, they confirmed the identity of the mystery artifact. 
 
 Enlarge this image toggle caption University of Warwick University of Warwick 
 
 "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," Williams said in a statement. 
 
 "Usually we are working on engineering-related challenges, so to be able to take our expertise and transfer that to something totally different and so historically significant was a really interesting opportunity." 
 
 For Mearns, the confirmation marked an important milestone for a project that dates back nearly two decades. The shipwreck Esmeralda was discovered off the coast of Oman in 1998, and Blue Water Recoveries has been collaborating with the country's Ministry of Heritage and Culture on its excavation for roughly four years. 
 
 And though it's believed astrolabes were in use long before the end of the 15th century, the BBC reports this one is only the 108th confirmed and cataloged — and the oldest one "by several decades." 
 
 "It's a great privilege to find something so rare, something so historically important," Mearns said, "something that will be studied by the archaeological community and fills in a gap." ||||| This November 2015 photo released Monday, May 21, 2018, by the Woods Hole Oceanographic Institution shows ceramic jars and other items from the 300-year-old shipwreck of the Spanish galleon San Jose on... (Associated Press) 
 
 BOSTON (AP) — A Spanish galleon laden with gold that sank to the bottom of the Caribbean off the coast of Colombia more than 300 years ago was found three years ago with the help of an underwater autonomous vehicle operated by the Woods Hole Oceanographic Institution, the agency disclosed for the first time. 
 
 New details about the discovery of the San Jose were released on Monday with permission from the agencies involved in the search, including the Colombian government. 
 
 "We've been holding this under wraps out of respect for the Colombian government," said Rob Munier, WHOI's vice president for marine facilities and operations. 
 
 The exact location of the wreck of the San Jose, often called the "holy grail of shipwrecks," was long considered one of history's enduring maritime mysteries. 
 
 The 62-gun, three-masted galleon, went down on June 8, 1708, with 600 people on board as well as a treasure of gold, silver and emeralds during a battle with British ships in the War of Spanish Succession. The treasure is worth as much as $17 billion by modern standards. 
 
 The Massachusetts-based WHOI was invited to join the search because of its recognized expertise in deep water exploration. The institute's autonomous underwater vehicle, REMUS 6000, helped find the wreckage of Air France 447 in 2011, which crashed in 2009 several hundred miles off the coast of Brazil. 
 
 It was REMUS 6000 that in November 2015 took some side sonar images that found the San Jose in more than 2,000 feet (600 meters) of water. 
 
 The vehicle descended to 30 feet (9 meters) above the wreck to take several photographs, including some of the distinctive dolphin engravings on the San Jose's cannons, a key piece of visual evidence. 
 
 "The wreck was partially sediment-covered, but with the camera images from the lower altitude missions, we were able to see new details in the wreckage and the resolution was good enough to make out the decorative carving on the cannons," said WHOI engineer and expedition leader Mike Purcell. 
 
 "It was a pretty strong feeling of gratification to finally find it," said Munier, who was not at the site but learned in a phone call from Purcell. "It was a great moment." 
 
 The treasure has been the subject of legal battles between several nations as well as private companies. Several weeks ago, UNESCO, the United Nations cultural agency, called on Colombia not to commercially exploit the wreck, whose exact location remains a state secret. 
 
 As for the treasure, that remains on the sea bed — for now. ||||| The vessel is the first of its kind to have been discovered relatively intact and dates from a series of attempts by Kublai Khan, emperor of the Yuan Dynasty, to subjugate Japan between 1274 and 1281. 
 
 Researchers have previously only been able to recover anchor stones and cannonballs from the scattered wrecks of the Mongol fleets and they believe that this latest find will shed new light on the maritime technology of the day. 
 
 The warship was located with ultrasonic equipment about 3 feet beneath the seabed at a depth of 75 feet. The archeological team, from Okinawa's University of the Ryukus, had been carrying out a search of the waters around Takashima Island, in Nagasaki Prefecture, because the area had yielded other items from Mongol ships. 
 
 Historical records suggest that some 4,400 ships carrying 140,000 Mongol soldiers landed in Japan in 1281 and skirmished with samurai in northern Kyushu. But after returning to their boats, the fleet was struck by a devastating typhoon that put an end to the invasion plans - a storm known to all Japanese as "kamizake," meaning divine wind, and again invoked in the dying days of the Second World War. 
 
 The researchers believe the boats tried to find shelter in the coves of northern Kyushu, an assumption borne out by the discovery by Professor Yoshifumi Ikeda's team. 
 
 "I believe we will be able to understand more about shipbuilding skills at the time, as well as the actual situation of exchanges in East Asia," Ikeda told reporters in Nagasaki on Monday. He added that more research remains to be done, but he is also considering raising the wreck and putting it on public display. 
 
 A section of the ship's hull was first found last year but a full archeological excavation only began on September 30. 
 
 The researchers uncovered a keel nearly 50 feet long and more than 1.5 feet wide. Lengths of wood planking were still buried beneath silt alongside the main spars, they said. 
 
 The planks were as much as 9 inches wide and nearly 4 inches thick and were still coated in a grey paint. The planks had been held in place by nails and more than 300 bricks that were used as ballast were located throughout the site, along with ink stones and shards of Chinese ceramics. 
 
 The archeologists have also recovered weapons and identified the remains of the ship's ribs and bulkheads. 
 
 The mast and upper structures have been lost, the researchers said, but historians are marvelling at the discovery of the first near-complete pre-medieval wooden ship in Japan. 
 
 Kosuka Umazume, director of the Japan Society for Nautical Research, said it was a "miracle" that so much of the vessel had been recovered in such good condition and after such a long period of time.
– The world's earliest known navigational tool used by Vasco da Gama's fleet was discovered in a shipwreck off the Oman coast, NPR reports. Called a marine astrolabe, it's believed to date from 1495 to 1500. Unlike the Game of Thrones intro astrolabe, sailors used this one to figure out where they were on the high seas. It was found in the wreck of the Esmeralda, part of the Portuguese explorer's armada. Da Gama, who discovered the first sea route from Europe to India, was returning home from his second trip there when he left some ships in the Indian Ocean to "disrupt maritime trade," meaning pillage. Several of the ships sank during a fierce storm in 1503. The Esmeralda was discovered in 1998. Since excavations began in 2014, University of Warwick researchers have recovered 2,800 artifacts, the jewel of the cache being the astrolabe, a bronze disc measuring 7 inches in diameter. Emblems depict the Portuguese coat of arms and the personal stamp of King Dom Manuel I. "It was like nothing else we had seen, and I immediately knew it was something very important because you could see it had these two emblems on it," team leader David Mearns of Blue Water Recoveries tells the BBC. "It's a great privilege to find something so rare, something so historically important." At first, the team wasn't 100% sure it was an astrolabe, but laser scans revealed navigational marks around the edges every 5 degrees, which sailors would have used to calculate their location by measuring the sun's position above the horizon at noon. (A ship that sank in 1BC may hold priceless treasures.)