It was how Odysseus sailed the seas, how Columbus reached the Americas, and how Lawrence of Arabia found his way across the vast, featureless deserts of the Middle East.
For millennia, travellers used the stars to guide them on their journeys ‚Äď a technique which, in recent decades, has been replaced by modern technology.
But now the US navy is reinstating classes on celestial navigation for all new recruits, teaching the use of sextants ‚Äď instruments made of mirrors used to calculate angles and plot directions ‚Äď because of rising concerns that computers used to chart courses could be hacked or malfunction.
‚ÄúWe went away from celestial navigation because computers are great,‚ÄĚ said Lt. Cmdr. Ryan Rogers, the deputy chairman of the naval academy's Department of Seamanship and Navigation. "The problem is there's no backup." ...