500-year-old astrolabe in shipwreck is our earliest known navigation tool

Archeologists have found what they believe to be the oldest astrolabe so far, a 500-year-old navigational tool, among a shipwreck led by Vasco da Gama himself.
The tool, believed to have been from the years 1495-1500, was recovered from the shipwreck of a Portugese explorer ship, which sank during a storm in the Indian Ocean in 1503.
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The ship, named the Esmeralda, was part of a fleet led by famed Portuguese explorer Vasco da Ga