Navigating with the Stars

Long before the luxury of modern navigation, ancient helmsmen looked to the heavens


While it’s profound to observe a star-spangled sky offshore mirrored by glass-still water, most boaters out in the deep don’t rely on the heavens to get back home. Nearly all captains today utilize onboard navigation technology to maintain their course. Before the advent of GPS, radar and chart plotters, seafarers of old used the skies for guidance — what’s known as celestial navigation. Amid a sea of darkness, stars have served as bespeckled beacons to generations of wanderers.

Pioneers of Polynesia

Tahiti | Credit: Julius Silver-Pexels

Roughly 4,000 years ago, ancestors of today’s Polynesians began arguably one of the greatest migrations in human history. From present-day Taiwan, early voyagers spread eastward across the Pacific for millennia to settle the 800,000-square-mile Polynesian Triangle that connects Hawaii, New Zealand and Easter Island.

Pacific Islanders conquered the planet’s largest ocean with no instruments whatsoever by developing a highly evolved navigational system known as “wayfinding” that interpreted their entire environment, including the sun, moon and stars.

On dark, clear nights, constellations like Nao Kao, or “The Darts” (Orion’s Belt), provided lane markers to monitor changes in latitude. Committing these star paths to memory was critical for return trips. Voyages could last four weeks or longer, during which wayfinders would only sleep two or three hours per day. Memorizing the risings and settings of over 150 stars served as the navigator’s internal “star compass.”

Polynesian adventurers pushed toward an uncertain horizon. Celestial navigation was still in use when Europeans discovered Polynesia in the 17th century. On his 1774-1775 trip to Tahiti, Spanish Captain José de Andía y Varela was astonished to see sailing masters there traveling the 120-150 miles to neighboring Raiatea without a mariner’s compass. He noted in his journal, “When the night is a clear one, they steer by the stars.”

Iceland spar that was allegedly used as a sunstone by the Vikings | Credit: Arni Ein - CC BY-SA 3.0 via Wikimedia Commons

Viking Voyagers

A few hundred years after the Polynesians, waves of seafaring Scandinavian warriors sailed westward between 800 and 1100 A.D., settling Britain, Iceland, Greenland and even parts of North America. Otherwise known as Vikings or Norsemen, these skilled mariners also used their knowledge of the skies to aid their conquest.

Referencing the sun by day, specially trained Viking navigators applied instruments such as the pelorus, sun shadow board, bearing dial and sun compass to determine latitude and direction. Used like a magnetic compass, these devices would help Norse sailors find geographic north based on the position of the sun’s shadow.

When skies were obscured by clouds or fog, Vikings may have pulled out a light-fracturing crystal called a sunstone to filter sunlight and track the sun’s position in the sky. Theories suggest that sunstones enabled Norsemen to navigate overcast days and even assisted transatlantic crossings to North America.

Known today as Iceland spar or optical calcite, this intriguing crystal is mentioned in Viking lore. One 13th century saga featured a man named Sigurd who correctly estimated the position of “the invisible sun” using a sunstone. History buffs beware: Archaeologists have yet to find a sunstone among Viking shipwrecks or settlement sites.

By night, Norse navigators used Polaris (the North Star) extensively as a navigational guide. Steering westward across the North Atlantic in summer, they measured the distance between Polaris and the horizon to determine latitude.

Colonial Captains

Navigators of early modern Europe also employed celestial navigation, starting when Portuguese explorer Vasco da Gama set sail to find passage to India in 1497. After rounding the African continent from the Atlantic to the Indian Ocean, da Gama picked up a skilled navigator who used a celestial device called a kamal. Essentially just a piece of wood connected to string with strategically placed knots along it, the kamal was first invented by 6th century Arabian sailors and measured stellar elevations to determine latitude, primarily Polaris.

Returning with his newfound instrument, da Gama introduced celestial navigation to Europe, and those navigators later evolved the kamal into easier-to-use versions called the cross-staff and backstaff. The mariner’s astrolabe was also introduced around this time, used to track heavenly bodies for navigation. Coincidentally, the oldest known astrolabe was recently recovered from the wreck of the Esmeralda, one of da Gama’s ships downed in a 1503 storm.

What followed in the 16th through 18th centuries was a revolution in navigational education in the name of trade and colonization. Although highly lucrative, a career in conquering and profiteering was extremely risky. To train conquistadors and pirates, navigational schools popped up all over Europe.

The curricula of these navigational institutes combined celestial navigation techniques with cutting-edge mathematics of the day, resulting in equal parts cosmography and trigonometry. Far from drunken sailors, master navigators were skilled mathematicians who earned triple what any able seaman made.

The celestial and mathematical ultimately culminated in the 18th century, when a British scientist and captain collaborated on a device that could be easily used on a moving ship whether in windy or otherwise bad conditions. Called a sextant, this useful instrument required little more than a steady hand and a good eye to determine latitude and longitude, changing the celestial navigation game forever.

Celestial Navigation in the Modern Era

A Navy quartermaster takes a sun sighting from the USS Alaska in 1945 | Credit: U.S. Naval Institute Photo Archive

The practice of steering by the stars still lives on today. NASA applies the principles of celestial navigation during its space missions, and the U.S. Naval Academy in Annapolis, MD, teaches celestial navigation techniques to midshipmen.

In 1973, renewed interest in ancient wayfinding techniques led the Polynesian Voyaging Society to build a replica of a traditional double-hulled canoe called Hōkūle’a. Using only traditional, non-instrument methods aboard, a crew of 15 men successfully sailed Hōkūle’a from Hawaii to Tahiti in 1976 in 30 days. More recently in April 2022, Lehua Kamalu made history as the first woman to navigate the 2,400-mile journey from Hawaii to Tahiti using wayfinding methods. She completed the trip in a mere 17 days.

In another instance, 73-year-old French sailor Jean-Luc Van Den Heede circumnavigated the globe to win the Golden Globe Race in 2018. Completely alone and using just a sextant, chronometer and paper charts aboard his 36-foot boat, he circled the planet in 212 days.

What can we learn from the courageous spirit of early navigators and those still practicing celestial navigation today? Facing unimaginable odds and unpredictable seas, a common thread among these legendary mariners is their distinct character — as anthropologist Sir Arthur Grimble put it, “The instinct of men to keep windward, to go uphill first, to oppose for the sake of opposing.”

The next time you look up at a starlit sky, remember our seafaring ancestors: hardy, self-reliant and perfectly attuned to the clockwork of the universe. The stars beckon us to heed the call. Get out on the water and juice this fall boating season for all it’s worth.

Gaze at these Celestial Events this Fall

As nights get longer this autumn, look for these dazzling attractions in your night sky. Hint: For help finding some of these events in your location, try using a stargazing app on your smartphone or tablet. My personal favorite is Night Sky.

The Milky Way | Credit: Wallpaperflare

October 8-9: Draconids Meteor Shower

Producing about 10 shooting stars per hour, the Draconids is best viewed just after nightfall. Viewed best from the Northern Hemisphere, it can be seen near the stars Eltanin and Rastaban at the head of the constellation Draco the Dragon.

October 14: Annual Solar Eclipse

The moon will pass directly between the earth and sun near its farthest point from earth, allowing for the outline of the Sun to still be seen. Annual solar eclipses are also known as “ring of fire” eclipses.

October 20-21: Orionids Meteor Shower

Orionids meteors are made up of dust grains left behind by Halley’s Comet, which has been observed since ancient times. Watch for up to 20 meteors per hour near the upraised club of Orion the Hunter.

November 4-5: Taurids Meteor Shower

Perfect for viewing from a boat offshore, Taurids meteors are best seen far from city lights near the Pleiades, above the constellation Taurus.

November 17-18: Leonids Meteor Shower

Enjoyed best just before dawn, this show can be seen near the constellation Leo.

December 13-14: Geminids Meteor Shower

If there’s one meteor shower to catch this autumn, it’s the Geminids. Considered by many to be the best shower in the heavens, watch up to 120 colorful meteors per hour radiating from near the star Castor in the constellation Gemini. A nearly new moon should make this a particularly wonderful show.

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