Answer: Eratosthenes was the first to propose a system of longitude between 260 - 201 B.C. Greek astronomer Hipparchus was the first to use longitude to define a location (along with latitude). Longitude lines run from the North and South Poles and are measured by one arcdegree. These lines are called meridians. Unlike latitude, longitude was not able to be determined until the 18th century as a result of difficulty. The Royal Observatory in Greenwich, England marks zero degrees longitude. Longitude was accepted after the 18th century after it was able to be determined and measured by mathematics.
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