27 Oct 2013

History of Navigation

Birds do it, bees do it—and so do aviators. “It” is navigation. Anyone on a long journey needs to be able to find their way to their destination quickly and safely, and then find their way home again. Today’s aviators have many different navigational tools at their disposal, from charts to global positioning systems (GPS) to ground-based transceivers. Until relatively recently, however, navigation was not always so straightforward. This article, presented by Spartan College of Aeronautics and Technology, gives a brief introduction to the early history of the navigator’s craft, which began with sailors and was passed on to aviators. Long before the advent of aviation, sailors traveled the seas on voyages of discovery or commerce. The first mariners would stay within sight of land, sailing from harbor to harbor. However, this could prove perilous in bad weather along rocky coastlines. Also, if people could not find a way to work out their position in open water, they were limited in how far they could travel. The question was, how could you find landmarks when you couldn’t see the land?

Solar Navigation
One method was to use the position of the sun as a reference. The Phonecians understood that the sun rose on one horizon and set on the other. In fact, their words for “sunrise” and “sunset”, asu and ereb became the roots of the names of Asia, the eastern continent known to them, and Europe, the western.[i] Later navigators would work out how to track the sun’s position in the sky to determine how far south or north they had traveled—the basis of modern-day latitude.

Animal Navigation
Another navigational strategy was to track birds: sea birds carrying food in their mouths would invariably head in the direction of their nests on land. You may remember the Biblical story of Noah and the dove as one example of this. There is also the tale of a Viking mariner called Floki, who took three ravens with him as he set out for Iceland. He released them at different times during his voyage. The first flew back in the direction they were sailing from. The second circled and came back to the ship. The final one headed off to the northwest, and never returned. Following it, Floki found his way to Iceland.[ii]

Wave Patterns
The Polynesians, who populated the Hawaiian and other far-flung islands in the Pacific Ocean thousands of years ago, were among the most skilled early navigators. They managed to cross vast open-water distances in primitive canoes. In addition to using solar, animal, and celestial strategies, they closely observed the swell patterns of waves to determine where the prevailing currents would take them, and where land might be. They also came to understand that clouds would cluster close to islands over a certain size. Most impressively, the Polynesians were able to record their knowledge without having yet developed a written language. They composed and memorized elaborate songs to pass on their understanding of the ocean. They also built elaborate navigation devices made of twigs, showing the prevailing currents and locations of islands—the earliest known navigational charts, or maps.[iii]

Celestial Navigation
Almost all seafaring cultures quickly adopted the stars as their landmarks in the open sea. Knowing the positions of certain stars could help sailors work out how far north or south they were, the time of night, the direction in which they were headed, and more. Northern cultures used Polaris, the North Star, to help them determine their latitude at night. As humans became more mathematically sophisticated, navigators found ways to determine their position more exactly using the stars. For example, Islamic astronomers made important contributions to the art of celestial navigation during the medieval period by inventing devices that could be used to measure the position of the stars, such as the kamal and the sextant.[iv] The US Air Force Academy taught celestial navigation until 1997, when computer technology had advanced sufficiently to make the practice unnecessary.[v]

The Magnetic Compass
The Chinese are generally credited with being the first people to understand magnetic compasses and use them for navigation. Lodestones, magnetic stones that align themselves in a north-south direction, had been used by the Chinese to tell fortunes. Once they began to realize that the lodestones always pointed north-south, however, they put them to use for more practical purposes.[vi] They designed a base for the lodestones that included the four directions and certain constellations, and began to use them on ships to keep track of their direction, whatever the weather. This practice is first recorded in Chinese manuscripts dating to the 1100s.[vii] As the Chinese began to travel more widely, the other cultures they encountered adopted, adapted, and refined the use of this navigational aid.