00:00 Navigation on the open ocean is difficult, especially when it comes to determining longitude, a problem that was unsolved for centuries.

01:40 European navigators faced more challenges in their exploration of the Pacific Ocean compared to the Polynesians due to their larger, lower-sitting ships and the prevalence of underwater hazards, highlighting the importance of accurate mapping and the need to determine latitude and longitude for successful navigation.

02:50 The latitude of a location could be determined by measuring the angle between the pole star and the horizon, but determining longitude was a much more difficult problem that required knowing the local time and the time at a fixed location.

04:05 Astronomical techniques such as lunar distance and the positions of Jupiter's moons could determine local time and longitude, but were not effective on a ship at sea.

05:16 John Harrison developed an accurate clock, called H5, that was able to determine longitude at sea with great accuracy, but he never officially claimed the prize for solving the problem of longitude.

06:35 Harrison's clocks were used by the British Navy and proved their worth, leading to improved navigation and safer voyages.

07:43 The pursuit of longitudinal measurement led to the development of wireless communication, global time signals, and ultimately the global positioning system (GPS), which allows for precise measurement anywhere on Earth.