Navigation

Navigation is the study and practice of guiding a craft or vehicle from one point to another while keeping track of its movement. It covers four main types: land, marine, aeronautic, and space navigation. The word comes from the Latin *navigatio*, which traces back to *navigare*—meaning to sail, steer a ship, or go by sea. Every method of navigation works by figuring out where you are in relation to known places or patterns.

In marine navigation, the goal is to move ships, boats, or other watercraft safely on or under the water. This is done using positions from navigation equipment and either electronic or paper nautical charts. The SOLAS Convention requires certain navigation gear on ships, depending on the vessel’s size. Land navigation involves moving people, animals, or vehicles across urban or rural areas using tools like compasses, GNSS receivers, maps, and visual markers. Aeronautic navigation means piloting an aircraft from one location to another while tracking its position throughout the flight.

The earliest known form of open-ocean navigation was practiced by Polynesians, who relied on memory and observation, recorded on instruments like the Marshall Islands Stick Charts of Ocean Swells. They used stars, weather, wildlife, and wave patterns to find their way between islands. One of the first proper navigation tools was the compass, with early versions appearing in China during the Han dynasty (around 206 BC). It was later adapted for sea travel by the Song dynasty in the 11th century. The compass first appeared in Western Europe and the Islamic world around 1190.

During the Middle Ages, maritime navigation in the Mediterranean began using scientific instruments like the mariner’s astrolabe. While land astrolabes had existed since Hellenistic times and were used in classical antiquity and the Islamic Golden Age, the oldest record of a sea astrolabe comes from Spanish astronomer Ramon Llull in 1295. Portuguese navigators later perfected this instrument during the early Age of Discovery. The first known guide on making and using a sea astrolabe was written by Spanish cosmographer Martín Cortés de Albacar in his 1551 book *Arte de Navegar*, based on the archipendulum principle used in building the Egyptian pyramids. However, the first altitude-measuring tool widely used at sea was the quadrant, reintroduced by Leonardo of Pisa in the 13th century and first recorded in use by Diogo Gomes in 1461. The cross-staff, known from the 14th century and believed to come from early Arab navigators, was also used but had many errors and was hard to use because it required squinting at the sun. These problems were solved by John Davis’s invention of the backstaff in 1595.

Widespread open-sea navigation using the astrolabe, quadrant, backstaff, and compass began in the 15th century during the Age of Discovery. The Portuguese, sponsored by Prince Henry, started exploring the Atlantic coast of Africa in 1418. In 1488, Bartolomeu Dias reached the Indian Ocean via that route. In 1492, Spanish monarchs funded Christopher Columbus’s voyage west across the Atlantic, leading to the discovery of the Americas. In 1498, a Portuguese expedition under Vasco da Gama reached India by sailing around Africa, opening direct trade with Asia. The Portuguese soon sailed further east, reaching the Spice Islands in 1512 and landing in China the following year. The first circumnavigation of the Earth was completed in 1522 by the Magellan-Elcano expedition, a Spanish voyage led by Portuguese explorer Ferdinand Magellan and finished by Spanish navigator Juan Sebastián Elcano after Magellan’s death in the Philippines in 1521.

For sailing ships, charting and course-recording methods also advanced. One of the oldest surviving marine charts, the Carta Pisana, was drawn on sheepskin and dates to 1275. On land, better map production improved navigation for armies, traders, and other travelers. Because paper charts were expensive and rare, sailors used tools like the traverse board and traverse tables (the oldest known traverse tables date to 1428) to record course changes and tacks without wearing out the charts. The quadrant was further refined by inventors such as Robert Hooke, Isaac Newton, and John Hadley, leading to the invention of the octant.

Mathematics also played a key role in navigation history. Developments like meridional parts, spherical trigonometry, and logarithms allowed navigators from the 1700s onward to navigate more accurately. On land, new mathematical tools and instruments advanced surveying and triangulation, which in turn improved maps.