International Date Line International Date Line The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups. The IDL is roughly based on the meridian of 180° longitude, roughly down the middle of the Pacific Ocean, and halfway around the world from the Greenwich meridian. In many places, the IDL follows
Longitude rewards in 1714. Monarchies in Portugal, Spain, and the Netherlands offered financial incentives for solutions to the problem of longitude as early as 1598. Addressing the problem of longitude fell, primarily, into three categories: terrestrial, celestial, and mechanical. This included detailed atlases, lunar charts, and timekeeping mechanisms at sea. It is postulated by scholars that the economic gains and political power to be had in oceanic exploration, and not scientific and technological curiosity, is what resulted in the swift passing of the Longitude Act of 1714 and the largest and most famous reward, the Longitude Prize being offered. In the early