019 Compass and Navigation

What this episode covers

The magnetic compass has been the most important instrument used for navigation since the beginning of the European voyages of discovery and until satellite positioning was introduced. The principle of functioning is dependent on the magnetic field of the Earth. It is not a recent invention and a form was used for divination in China since 200 BCE. It was used for navigation first in the 11th century in China and probably it was introduced from there to Europe in the 12th century through trade routes. The of the compass for navigation is testified by the effort put by nations to measure the magnetic field of the planet, to determine the position of the magnetic north pole and to investigate its yearly movement. One of the famous expeditions to pursue such investigations was the Franklin voyage in search of the Northwest Passage. The Vikings who navigated areas close to the magnetic pole, which makes the magnetic compass unusable, most probably used a sun-based compass, that could also be used to determine variations in latitude during a voyage, and they might even have been able to use this system in conditions of bad visibility usign a crystal of calcite as polarizing filter. The next revolution for polar navigation came with the invention of the gyrocompass. Nowadays navigation is greatly symplified and made accessible to private and professional users through satellite systems like GPS, GLONASS and GALILEO and BeiDou which can be accessed using dedicated receivers or apps on mobile devices.