From Sails to Satellites: The Origin and Development of Navigational ScienceWhen Hipparchus invented the coordinate system of latitude and longitude, a rough latitude could be found, at least on land, with solar measurements, but it would take another two thousand years before longitude could be measured accurately at sea. Indeed, before the perfection of the sextant and chronometer in the 18th century, sailors navigated on long voyages without knowing where they were for much of the time. In 1991, in contrast, single seater