Thousands of years ago, the oceans seemed a lot wider, even unnavigable. Before mariners developed tried-and-true navigation techniques, sailing the seas involved a lot of guesswork — or, if you want it to sound cooler, “dead reckoning.”
Slowly, our ancestors moved beyond their initial stabs in the dark. Some looked to the sky, using their new knowledge about the cosmos to help them better understand life on Earth. Others took a keen interest in the seas, learning to intuitively navigate the vast expanses based on their currents and swells.
Nowadays, we have a relatively easy time getting around — thanks, GPS! — but it took a long time to get here. How were Polynesians able to cross thousands of miles of open ocean more than 3,000 years ago? Which seafaring society might have successfully used crystals to find their way? What persistent navigation myth just won’t die? Read on and get your sea legs with these six facts.
Polynesians were pioneers of the open ocean
In the early days of ocean navigation, explorers stayed pretty close to the shoreline and used visible landmarks to mark their position. However, Polynesians, the first developers of open ocean exploration, set off from New Guinea and moved eastward in about 1500 BCE. After first traveling to the adjacent Solomon Islands, they gradually journeyed farther and farther east. Their vessel of choice was a double canoe with two hulls connected by crossbeams, kind of like a catamaran.
Venturing out into the open ocean, these explorers eventually reached Fiji, Tonga, Samoa, and Tahiti. They then traveled more than 2,600 miles north to Hawaii — longer than the distance across the U.S. from Portland, Maine, to Seattle, Washington. By roughly 1,000 or possibly 1,200 CE, the descendants of those early explorers populated the entire Polynesian Triangle, the three corners of which are Hawaii, Rapa Nui (aka Easter Island), and New Zealand.
The Polynesians didn’t have any navigational instruments that we know of, so how did they do it? Although their navigation techniques were passed down orally, historians think they navigated using stars, ocean swells, the sun, the moon, and migratory birds. Some Pacific Islanders navigated simply by using the waves themselves. In 1976, a group of Polynesian canoeing enthusiasts made the Tahiti-Hawaii trip using no navigational instruments and a traditional voyaging canoe — a feat that’s since been repeated several times.
Some early nautical charts were made of sticks and shells
A nautical chart provides not only topographical information, but also details about the behavior of the sea, such as how tidal patterns interact. Today, we can easily read this data on screens and paper, but ancient Micronesian navigators called ri-metos recorded their knowledge using elaborate “stick charts” made from palm strips, coconut strips, and cowrie shells.
As you might imagine, these charts weren’t especially portable, so they were designed to be memorized before a voyage. The charts didn’t follow any kind of uniform style, and some of them were only designed to be read by the person who created them, so they can be hard for modern viewers to interpret. We do know, though, that some charts depicted general ocean patterns, while others contained precise piloting instructions.
Early magnetic compasses bore little resemblance to modern ones
Today, magnetic compasses are so ubiquitous that we just call them “compasses.” They contain a magnetized needle that naturally lines up with the Earth’s magnetic field, so the ends point to magnetic north and magnetic south (moving targets that are fairly close totrue north and true south, but that can lead to errors when traveling very far north or very far south).
Scientists don’t know for sure who made the first compass, but they believe the first compasses to be used for navigation came from 11th- or 12th-century China. The first European usage of a compass was recorded at the end of the 12th century. These early prototypes used lodestones (pieces of naturally-occurring magnetic ore) or needles magnetized with lodestones that were then attached to sticks or corks so they could float in water.
At first, magnetic compasses were used primarily as backup navigation aids, but as engineers got more savvy, compasses became more reliable. By the 13th century, the compass’s design had graduated to a magnetized needle mounted on a pin at the bottom of a bowl. In time, a directional card with the 32 principal points of direction began to be mounted beneath the needle. The design of the card itself evolved, too: The north point was first marked by a spearhead and a “T” for the Latin word Tramontana, meaning “the north wind.” Around 1490, these symbols were replaced with a fleur-de-lis, which is still commonly seen on compasses today.
Astrolabes weren’t only used for navigation
The concept of an astrolabe, a device used to measure the positions of celestial bodies, dates back to ancient Greece in the third or second century BCE — although its exact origin is unclear. By the ninth century CE, astrolabes were highly developed and utilized in Arabic cultures. The devices made their way back to Europe in the 12th century, and the mariner’s astrolabe was a standard piece of navigational equipment by the end of the 15th century, just in time for the Age of Exploration.
Astrolabes are used to determine the locations of celestial bodies relative to the user. A disk called a “mater” holds a series of smaller rotating and sliding disks — one with Earth’s latitude lines and another with well-known constellations and stars. A straight “rule,” or bar, spins around that, and a sight helps determine the altitude of the sun or another star that can then be used as an anchor point. Astrolabes often came with specific plates that corresponded to the different latitudes of certain large cities, because the sky’s geography is affected by one’s latitude.
While these devices were very useful for navigation, it wasn’t their only claim to fame: In the Islamic world, they helped determine prayer times and the direction of Mecca. During the Middle Ages in Europe, they were consulted to help with decision-making, much like modern horoscopes. And more mundanely, they could also be used for making topographical surveys.
Vikings may have used crystals to navigate
The Vikings, a group of seafaring Scandinavian warriors, were also skilled ocean navigators. They began to populate Iceland — around 500 miles from their native Norway — in about 900 CE, even eventually reaching North America. The specifics of their navigation techniques are somewhat mysterious, but recent research indicates they may have used crystals.
Because they sailed their longships in the far North Atlantic, Viking travelers benefitted from up to 24 hours of continuous daylight, but they encountered a lot of fog, too. Ancient Norse literature mentions “sunstones,” stones that helped their holders find the sun — and scientists now think these may have really existed. In 2011, researchers used calcite crystals to pinpoint the location of the sun within 1 degree. It’s not magic, although it sounds like it: Through polarization, crystals can show sunlight patterns that can’t be seen with the naked eye.
Another study from 2014 suggests these crystals may have been used in conjunction with a sun compass. Researchers simulated 3,600 trips between Norway and Greenland at the spring equinox and summer solstice, two dates marked on a disc believed to be a component of a sun compass. They found that by checking the crystals every few hours, the computer-generated voyages successfully reached Greenland 92% of the time.
That study hasn’t been replicated in the real world yet, but it offers some clues to how Viking navigators were able to navigate without the use of magnetic compasses or astrolabes.
Navigators knew that the Earth wasn’t flat earlier than you might think
There’s a persistent myth that Christopher Columbus “proved” the Earth was round in the 15th century during his voyage from Europe to the Americas, but he was many centuries too late. In fact, formally educated people knew the world wasn’t flat starting way back in the third century BCE, while scientists and mathematicians may have known as early as the sixth century BCE. Columbus’ surprise landing in the Americas had nothing to do with thinking the Earth was flat — he just thought the global circumference to be smaller than it is and believed he’d end up in Asia. This tenacious myth comes from a highly embellished 1828 biography of Columbus written by Washington Irving, better known for fictional works such as “The Legend of Sleepy Hollow” and “Rip Van Winkle.”
Like the aforementioned scientists and scholars, mariners were aware of the world’s roundness very early on. Sailors observed that when viewing distant ships, the tops of sails and masts were visible before the decks and hulls of the vessels to which they were attached. And as they traveled to different points of the Earth, they also noted being able to see different constellations. Celestial navigation would have been pretty difficult otherwise.
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