Off-Nominal - 03b - From Tahiti to Hawai'i (post-Episode 3 Bonus Content)

Episode Date: December 5, 2017

Note: Please listen to Episode 3 before listening to this podcast! A companion podcast to follow Episode 3. Jake tells the story of Polynesian Celestial Navigation. Originally produced for a class in sound design but published here for your enjoyment. Covert art courtesy of the Hubble Space Telescope (NASA/ESA/Hubble)

Hi, my name's Jake and this is Stargazers. Each week we tell a story about people and how the sun, the stars, the moon, and the sky play a role in their lives. Episode 1, from Tahiti to Hawaii. It's a bright, sunny spring day and you're on the beach. Your crew is busy loading food and supplies on a wooden, double-hauled ocean canoe marked by two towering masts. You squirm your toes in the sand and the lush tropical land of Tahiti over your shoulder is behind you. Ahead, you stare north out to sea, the vast Pacific Ocean staring straight back at you. Your captain asks if you are ready and you nod.

It's time for you to guide the ship because you are a Polynesian navigating. Your destination is the island chained of Hawaii, over 4,000 kilometers north from the other side of the equator. If it were today, you could rely on compasses and sextants or even GPS to navigate, but it is not today. thousand years ago the Polynesian people sailed the Pacific without instrumentation. They used the birds, the sea, the clouds, and the stars, combined with a healthy dose of institutional intuition and undoubtedly a little bit of luck.

To do this, the tribes of the South Pacific depended on the skills of a navigator. These elite citizens belong to storied guilds dedicated to preserving their unique abilities and passing on their knowledge from one generation to the next, through instruction, mentorship, stories, and song. But the Polynesians were not civilized in the way we used the term today in the West. They possessed no metalworks with which to build compasses or sextants, they had no written language with which to log coordinates or courses, and they had no form of long-distance communication.

How then were they so successful in populating so many islands spread over so wide a territory? As night falls on your first day at sea, the crew settles in for some rest, save a few steersmen holding a sail steady. But for you, the work of navigating continues. from the torches of the tribal villages or the seeping illumination of a 21st century city, the Pacific night sky is not a dark expanse marked only by a few of the brightest stars and planets. On the ocean, two millennia ago, the night sky is awash with celestial light. Thousands of stars trace familiar paths as they appeared across from east to west. The Milky Way,

unencumbered by the glow of light pollution, lights up the sky in a long band, marking the road by which the souls of Polynesian dead were thought to travel. Familiar constellations like Orion, Scorpius or the Southern Cross mark landmarks. To us, this light show may be a source of entertainment, but for the Polynesian navigator, this was a map. But how did they use it? On a human timescale, the stars appear more or less fixed from night to night, traveling the same path as the Earth rotates.

This means that any star rises in the same compass direction each night and sets in the same compass direction each night, provided you're observing from the same latitude. For example, in the Caroline Islands, 6 degrees north of the equator, the star Vega is seen to always rise in the northeast and always set in the northwest. By watching for these key stars as they cross the horizon, fairly accurate bearings can be estimated. Polynesian navigators made use of this celestial fact,

selecting stars and cataloging them in their own personal star charts to create a virtual compass in their mind. In order to ascertain any bearing at any time, multiple stars' positions and compass points were memorized, with some Polynesian mind maps containing upwards of 150 stars corresponding to 32 different directions. Knowing this many stars was also helpful when parts of the sky became obscure with clouds, and you were working with incomplete information. Learning these charts was a cultural practice honed over years and years.

Each island and sometimes each navigator would have their own chart, and different charts would need to be learned when traveling over long distances across different latitudes, as the star's apparent position changed with your vantage point. With the boat pointed in the right direction, now comes the hard part. How do you keep track of how far you've traveled day after day? Traveling north-south was in some ways easier, latitude is something that can be measured fairly reliably using the north star Polaris. Consider the horizon zero degrees and the zenith, the point above your head, as 90.

Polaris angle between those points is roughly equal to your latitude, so if the star is sitting 18 degrees above the horizon, you are roughly 18 degrees north of the equator. It turns out that measuring this angle is a simple enough task and something that was featured in the recent Disney film Moana. By holding out your right hand, palm forward, placing your thumb on the horizon, and then familiarizing yourself with where Polaris intersects your index finger, you can leverage your own natural protractor. Measuring distance traveled east to west was a much more challenging task, and to do it, navigators used a skill with a rather scary name, dead reckoning.

Dead reckoning involves two steps. understanding where you were yesterday and understanding how far and in what direction you traveled today. Using this information, you can make a reasonable estimation of where you are now. Simple, right? Well, not exactly. While we established that determining direction was easy enough, distance traveled is another thing. There were no odometers on Polynesian outriggers. Dead reckoning carries the risk of cumulative errors.

The mistakes you make on one day carry to the next and can add up over time. Complicating this further are the strength and direction of winds, and ocean currents altering your travel factor. For a navigator, this means an unending task of monitoring the sea conditions and continually updating the mental journey in your mind. It was something that required intense concentration. You could not afford to miss sudden changes in the wind or glimpse at the stars through the gap in the clouds to lock in your heading.

For this reason, many navigators did not sleep for long periods, instead settling for brisk naps through the day and night. Knowledge of trade winds and current zones was a benefit that veteran navigators could used to their advantage in their calculations, but ultimately it came down to keeping track, every minute of every day, the forces acting on your boat. Continually recording this daily addition to your course in your mind was a task of incredible memorization befitting a sciity with no written language. Perhaps only the mind of such a person accustomed to recounting stories and lore without the use of lists, could truly pull it off.

The final skill for a navigator was that of actually making landfall at your destination. You see, despite incredible levels of accuracy, it's simply very very very important. difficult to intercept a tiny island in the middle of the world's largest body of water. Most such locations could only truly be seen with the unaided eye within 10 or 15 kilometers. To narrow in on that final destination, navigators had a few different tricks up their sleeves. Cloud formations were a key indicator. The peaks of the volcanic islands in the South Pacific often caused clouds to part around them and form patterns visible for hundreds of miles. In some cases, the brilliant colors of the shallow water surrounding island change would even

reflect on the underside of clouds, giving navigators a hint that they were close. These shallow coastal waters also had an effect on the ocean swells. Navigators with extreme sensitivity could feel the ocean changing beneath the boat in a way that you could only do after years of practice. But the most important information to make these explorers aware of the nearby island was perhaps the simplest and most cliched of all. We've all seen this trick in the movies when someone is lost at sea and finally reaches land. The sight of birds.

Understanding the different species and how far they are willing to travel from land, gave the navigators of Polynesia great hints to the distance and direction of their island destinations. These three skills, knowing your direction, keeping track of your position, and narrowing in on your destination, enables the explorers of the ancient Polynesian world to colonize the vast expanse of dotted lands in the South Pacific. Island after island, these famed voyages spread their culture, their knowledge, and the incredible tradition of celestial navigation. Today, the art of celestial navigation is a mostly forgotten skill. In a world of GPS, such skills simply play no role.

But what about the stars? Do they still play a role in the culture of today's Polynesian people? Thankfully, yes. Far out in the solar system, beyond the outer planets, lies the Kuiper belt, a vast expanse of old, frigid rocks and minor planets. Bodies like Haumea and its moon Hi-Iaka and Namaka, as well as the dwarf planet Makeame, carry the names of Polynesian folklore,

preserving their culture in the vastness of space. In the islands of Hawaii, there is a particularly good seeing, which is how an astronomer would describe a really great place to look up. High on the slopes of the big islands of Hawaii, you can find a great Keck Observatory, one of the most important sites for astronomy in the world and ground zero for dozens of important discoveries. And in fact, just last month, on the island of Maui at the Haleakala Observatory, one of the most exciting discoveries was just made in the first recorded interstellar object, a rock from another star on an endless journey to visit our home. This rogue asteroid from somewhere else

careened through the solar system, passing around the sun and underneath the earth before heading off in another direction, never to be seen again. This extra solar rock is designated one eye, 2017 U1, but its informal name is Au Muamua, the Hawaiian word for scout. So while the practice of celestial navigation may no longer be relevant for the Polynesian people of today, their culture lives on in space, charting a course from one star to the next, as it has always been.