Oceanography is deeply connected to the histories of exploration, colonization, trade, war, and scientific disc discovery. Considered the world’s first seafarers, Polynesians migrated from the western coastline of the Pacific ocean about 30,000 years ago to colonize islands such as New Guinea, Fiji, Samoa, and Hawaii.
Polynesians navigated the open ocean using their knowledge of astronomy (the positions of stars and planets) and ocean currents. They used these data to create the first oceanographic maps. Shells and knots represented the location of islands, and curved pieces of wood represented the direction and strength of surrounding waves and currents. These stick charts were passed down and improved from generation to generation over 25,000 years.
Starting in the 1400s, European explorers used the sea to colonize new lands and establish efficient trade routes. Prince Henry of Portugal, nicknamed “Henry the Navigator,” created the first oceanographic institute where scholars and merchants learned about oceans, currents, and mapmaking.
These new studies prompted the age of exploration, in which European navigators and explorers such as James Cook, Christopher Columbus, and Ferdinand Magellan launched expeditions around the world. Important oceanographic tools were created and improved upon during this period, including the mariner’s compass, astrolabe, and chronometer. By keeping accurate time on a moving ship, the chronometer allowed sailors to figure out their longitude—a massive advancement in maritime navigation.
Military technology facilitated the study of our oceans. The use of submarines, starting in the American civil war, prompted the development of sonar and the magnetometer. Sonar measures distance by timing sound waves as they leave and return to a ship after bouncing off surrounding objects. Sonar enables scientists to measure distances from the ocean surface to the seafloor more accurately and efficiently than the rope depth-soundings of the Challenger era. The magnetometer, originally developed to detect the metal hulls of submarines, is used by oceanographers to measure the magnetic properties of the seafloor. These measurements have enhanced our understanding of Earth’s magnetic core.
Since the 1970s, sophisticated computer technologies have helped oceanographer’s measure ocean properties on a global scale.
In 1978, NASA launched SEASAT, the first civilian oceanographic satellite. SEASAT’s sensors measured wind speed and direction, sea surface temperature, polar sea ice conditions, and surface waves. SEASAT also provided satellite imagery of cloud, land, and water features. Although it was operational for only 105 days, SEASAT collected as much oceanographic data as the previous 100 years of ship-based exploration. Another NASA satellite, TIROS-N, produced the first maps of sea-surface temperature and ocean chlorophyll, a green pigment necessary for photosynthesis.
In the late 1970s, the National Oceanic and Atmospheric Administration (NOAA) began mooring a series of buoys across the tropical Pacific Ocean. Known as the Tropical Atmosphere Ocean array, this collection of 70 buoys sends oceanographic and atmospheric data to shore in real time through a satellite system. This data has improved our ability to predict global climate processes such as El nino.