Sun Moon Earth

The History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets


By Tyler Nordgren

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With beautiful illustrations and a detailed map, Sun Moon Earth has everything you need to get ready for the next solar eclipse.

On April 8, 2024, millions of Americans will experience an awe-inspiring phenomenon: a total eclipse of the sun. In Sun Moon Earth, astronomer Tyler Nordgren illustrates how this most seemingly unnatural of natural phenomena was transformed from a fearsome omen to a tourist attraction. From the astrologers of ancient China and Babylon to the high priests of the Maya, Sun Moon Earth takes us around the world to show how different cultures interpreted these dramatic events. Greek philosophers discovered eclipses’ cause and used them to measure their world and the cosmos beyond. Victorian-era scientists mounted eclipse expeditions during the age of globe-spanning empires. And modern-day physicists continue to use eclipses to confirm Einstein’s theory of relativity.

Beautifully illustrated and lyrically written, Sun Moon Earth is the ideal guide for all eclipse watchers and star gazers alike.



A Day with Two Dawns and Midnight at Noon

It’s not even lunch yet when something takes a bite out of the Sun. It’s only a tiny notch at first, all but invisible without my cardboard eclipse glasses. Were it not for the shouts from the crowd around me on this August day, I never would have noticed. But now that I’m watching, I can see the bite grow bigger. It is the edge of our unseen Moon. The Sun is being eclipsed.

It takes forty minutes for the dark notch to grow so big that the Sun is now a crescent. But even with most of the Sun covered, the heat of the day is still intense. I take off my glasses and take refuge under a tree. There in its shadow I see a thousand bright crescents swaying in the grass to the time of the breeze in the treetop. Every one of them is an image of the Sun, projected on the ground when each tiny gap in the leaves overhead acts as a camera obscura, a pinhole camera. Nearby children have spotted them too, and begin to yell and giggle as they point and play among the bright little arcs. Had I not known what was happening before, this oddity would certainly have revealed the eclipse in progress above.

After an hour has passed, only twenty minutes remain until totality begins. The life-giving nature of the Sun is no longer an abstract concept: the sky has grown darker and colors are strangely wrong. The landscape is sapped of saturation. The worlds are aligning.

With ten minutes left, the conditions change quickly. The world has turned to twilight. The shadows of trees sharpen, as if lit by a single spotlight. Instead of coming from a round yellow disk set amid a bright blue sky, all illumination now comes from a narrow white crescent in a colorless dark vault.

I put my glasses back on for these final moments of the partial phase and can see the remaining crescent shrink as I watch. The crowd rises. Conversations hush, and I notice for the first time that all birdsong has ceased; the birds have returned to their nests to sleep in the unexpected night. An unseasonably cool wind blows across my arm as the temperature drops. The eclipse becomes a multisensory experience of sight, sound, and touch. So little of the Sun is left that surely totality should begin at any second, but I can’t tear my eyes away to look at my watch. Even the passage of time seems affected. These last few seconds seem to expand rather than diminish.

Suddenly, the Sun’s thin sickle of light breaks apart into an array of brilliant specks that dance and shimmer along the Moon’s jet-black rim. They are called Baily’s beads—the last rays of the vanishing Sun streaming through actual mountain valleys along the curved lunar surface. I finally remove my protective glasses to see them quickly wink away until a glorious diamond ring appears—a single glistening star set in a band of white radiance encircling the Moon.

Then the spot collapses upon itself and is gone.

We have reached totality.

Where before there was light and heat, now there is only a cold, black hole in the sky surrounded by a ghostly crown. The corona, a ring of immense pearly tendrils, envelopes the darkness and stretches off into the sky in all directions. It is unimaginably beautiful and only ever visible during these few precious minutes of totality. All around it are the brighter stars and planets, invisible until now; it is a day that has become night at noon, with the Sun, Moon, planets, and stars overhead all at once.

As an astronomer I know the mechanics of this celestial alignment, yet in this moment of totality I fully understand the difference between knowledge and feeling. The hair is raised on the back of my neck and my mind screams at the wrongness of what I am seeing. It is no coincidence that cultures from all over the world witnessed this sight with some degree of dismay. The Greek origin of the word “eclipse” is ekleipsis, meaning omission or abandonment. Ancient Chinese eclipse accounts contain the characters for “ugly” and “abnormal.” For the Aztec, the eclipsed Sun “faltered” and became “restless” and “troubled.”

These reactions make perfect sense when you consider that the Sun is the giver of life. When the Sun goes away without warning, it leaves behind the fear that it—our life source—might not come back. It is clear to me now why people throughout time did what they did to scare away the demons, chase away the jaguars, and slay the monsters they imagined devouring the Sun. The French astronomer and historian Jean-Pierre Verdet has found that this fear-fueled call to action was universal.

In Paraguay and Argentina, the roar of the crowds and barking dogs frightened the celestial jaguar that ate the Sun. In Scandinavia, Norsemen yelled to frighten away the demon dogs that the god Loki had sent to hunt and feed upon the Sun and Moon. The Ojibwe of North America sought to help the beleaguered Sun by firing flaming arrows to help him regain his light. In India, the people banged pots and pans to frighten Rahu, an immortal head who chased and ate both Sun and Moon. If they were loud enough, Rahu, startled, would drop the Sun from his jaws: totality would be averted and the eclipse would be only partial. For the Aztec, however, matters were more serious: “The common folk raised a cry, lifting their voices, making a great din, calling out, shrieking. . . . People of light complexion were slain [as sacrifices]; captives were killed.”

Fortunately for any fair-skinned Aztecs, multiple total solar eclipses for any one location are rare. Though eclipses happen roughly twice each year, each one follows a different path across our planet. The patterns repeat in shape every eighteen years, but each time, the path is positioned one-third of the way around the planet and a little farther north or south than before. As seen from a location high above the globe, the paths slowly spiral around the planet from pole to pole until eventually any spot on Earth can expect, on average, to see totality every 375 years. Occasionally, the different paths do cross, and so every once in a while, the rare person in a particular spot may live long enough to see multiple solar eclipses over several decades.aa For cultures that looked to the sky for omens—where every new star, comet, or eclipse could be the sign of the end-times—imagine what seeing two total eclipses in one lifetime would have meant.

Though no total solar eclipse has touched the mainland United States between 1979 and 2017, the residents of Carbondale, Illinois, will be lucky enough to see two total eclipses in seven years: first in 2017, and again in 2024.

FIGURE 1.1. The three types of eclipses: solar eclipses occur when the Moon passes between Earth and Sun, while lunar eclipses occur when the Moon enters the Earth’s shadow. Annular solar eclipses occur when the Moon is too far away from the Earth to fully cover the Sun, leaving a single “ring of fire” in the sky. (Image by the author)

A thousand years ago, in what would become the American Southwest, Chaco Canyon was the ceremonial center of the Ancient Puebloan people (whom we used to call the Anasazi). There, on the side of a massive boulder, is a pictograph unlike any other. It features a large circle pecked into the yellow sandstone surrounded by strange looping tendrils similar in appearance to those of the solar corona. It is thought to be a record of the total solar eclipse of July 11, 1097, one of three solar eclipses (two of them total) visible there over a period of fifty-eight years at the height of their culture. To the upper left is a second small circle, precisely where Venus would have appeared at the moment of totality so long ago.

Imagine the effect such an apparition would have had for a Sun-watching people at the heart of their ceremonial society during a decade of extreme drought when the climate was changing for the worse. For a people in the midst of extreme cultural and environmental crises, might such an eclipse have been yet another contributing factor in what made the Puebloans, also called the Chacoans, eventually wall up their monumental “Great Houses,” set them aflame, and abandon their canyon?

Even today, eclipses play on our fears. The American anthropologist Ward Keeler described the event of June 11, 1983, when a total solar eclipse swept across Indonesia.

The air became very still and Java’s lush vegetation glowed in the eerie light characteristic of sunset in the tropics. As at sunset, too, the horizon turned red, but it did so not only in the west but in all directions, and in the half-light distant volcanoes usually obscured by the glare of the Sun became visible. For the four minutes of total eclipse, the Sun, almost directly overhead, looked like a black ball surrounded by a brilliant white light. Most eerily of all, in one of the most densely populated rural areas in the world, there was no traffic on the roads, no movement in towns or villages, and no one watching the eclipse.

For weeks prior to the event, newspaper reporters, radio announcers, and TV stations had gone to great lengths to warn people about the event for fear that they would damage their eyes peering up at the vanishing Sun. Posters were prominently displayed in villages across the country bearing the message that watching the eclipse would cause viewers to go blind. The warnings were so effective that residents stayed in their homes during the eclipse. They dared not even look outside for fear of the Sun’s “sharp rays.”

I know that mistaken fear firsthand. The last total solar eclipse to touch the continental United States did so in Portland, Oregon, on February 26, 1979. I was a boy, only nine years old then. In my fourth-grade class, we made clay medallions of the upcoming eclipse. While others painted black circles with yellow crescents in representation of the partial phase, I had found library books showing the corona, and so I carefully painted the billowing white ring around the central black hole. On the morning of the eclipse, my school canceled classes. Yet rather than go out and see the sight for myself, I hid indoors with the curtains drawn. Local TV and radio stations had been inundated with the exact same messages of fear that would later be broadcast all over Indonesia. I hid indoors, terrified of the same mysterious rays with the power to make me go blind if I so much as got a glimpse of the eclipsed Sun.

Today I know that there are no special rays, sharp or otherwise. The Sun is just as bright on any ordinary average day as it is on the day of an eclipse. During the time that the Sun is partially covered, it is still bright enough that staring at it for even a couple of seconds can cause permanent damage to the retina (just like on any other day). For this reason, eclipse glasses are necessary when the eclipse is partial; once totality begins and the Sun disappears, you can take your glasses off, and the spectacle is as safe as it is awesome.

Yet, in our zeal to be “safe,” we flood the airwaves with our fears, never with our hopes. That is why, to this day, my first eclipse memory is of watching the events unfold on my RCA color TV (snapping photos off the screen with my plastic drugstore camera). My only direct experience of the event itself was noticing how dark the house became as totality passed unseen overhead. It would be thirty-eight years before a total solar eclipse would touch this country again, and I have spent every one of those years wishing I’d turned around, gone to the window, parted the curtains, and simply looked up.

My career as an astronomer has taken me around the world since then, partly in pursuit of exactly that which I so narrowly missed when I was nine. Yet though I have seen multiple solar eclipses since, I will never be able to see the one I missed that day. Every eclipse is different. The shape of the corona, the streamers and jets that are such a startling phenomenon of totality, is dependent on the conditions taking place on the Sun at just that moment, and its exact shape is unknown until the instant of totality.

The search for meaning in celestial events is the purview of astrology. Astrological records of ancient China claimed that solar eclipses were a reflection of the quality of the king, and the corona’s appearance was said to reveal the political plots at work behind the throne: “[If the king] does not share his fortune with his subjects, the condition is called unstable. Then there will be a total eclipse with Sun being black and its light shooting outward. . . . If there are two ear-rings beside the Sun during eclipse while in the east, west, south, and north corners there are white clouds shooting outward, then the whole country will be in war.” But China is not the only place where the sky was searched for meaning: court astrologers all over the world have done the same for millennia. A comet appears in the sky? The king will be overthrown. A new star (a supernova) appears in the constellation of Leo? A new king will be born. The Sun is eclipsed? The king is wicked. As a steely-eyed scientist who prides myself on my reason and yet is moved to awe by such a rare and beautiful phenomenon, I can understand the ancients’ desire to associate eclipses with events of great importance.

If eclipses were thought to mark momentous events, then the reverse was also true: certain events that the original chroniclers wished to appear to be momentous were made so by adding an eclipse, even if no actual eclipse was handy. The end-times stories of Ragnarok and the Rapture in the Norse and Christian traditions, respectively (as well as the Crucifixion in the gospels), are accompanied by the Sun turning black. These details have often been interpreted as references to total eclipses, even if the description of the event, as in the case of the Crucifixion, bears little similarity to an actual eclipse.

Even in modern times, momentous events seem to have their associated eclipses. To anyone living in Boston, Massachusetts, the night the Red Sox broke their eighty-five-year-long World Series “curse” is as momentous as they come. It was made all the more so by the fact that it only happened during the final moments of the total lunar eclipse of October 27, 2004. At that instant, the Moon became red, as it was lit by the light of every sunrise and sunset happening on Earth at that moment. Perhaps the Red Sox could only win by the light of a red Moon?

For such an awe-inspiring sight, throughout most of history the ability to call it into existence was a sign of one’s power with the gods. A little over three hundred years after Columbus scared the Jamaican chieftains with his calculation of a lunar eclipse, another European thought he’d try the same trick with the Plains Indians in the American West. There, a local doctor in a small town in the Dakota Territory in 1869 read in his almanac that there was about to be a total eclipse of the Sun. Eager to impress upon the local Sioux the power of the White Man’s magic and healing arts, he told them the exact date and time the eclipse would begin. And it would last, he said, until he saw fit to stop it.

When totality occurred, the Sioux, rather than cowering in fear, raised their rifles and fired into the air. When the Sun came out again, they calmly stated that “the doctor could predict the eclipse, but they could drive it away.”

That eclipses can be predicted years in advance and all over the globe—and that people made these predictions for over a thousand years without computers—is truly remarkable. Wish to see a total solar eclipse? Astronomers can now tell you the location and time of any future eclipse, down to the mile and the second. More importantly, the proof of whether or not we are correct will be waiting for you when you get there: either you see the corona or you don’t. If you don’t, then we learn we didn’t understand the world as well as we thought, and we will seek to correct what we failed to get right. This is the power of science and the process by which we have learned everything we know about the physical universe in which we live.

Astrology, like astronomy, makes predictions. Astrologers claim that the position of the Sun, Moon, and planets at the time of your birth influences your personality and fate. It tries to identify auspicious dates, opportune investments, and compatible mates. The one thing it does not do, however, is reevaluate its assumptions when it’s wrong. Only science does that. Yet in a 2014 National Science Foundation survey, nearly half of all Americans (45 percent) responded that they believed there was some scientific basis to astrology. Imagine my disquiet when, during my most recent trip to the doctor, the nurse drawing my blood looked at my paperwork and said with a smile, “Oh hey, you’re a Scorpio too!”

The primal appeal of pseudo-sciences like astrology is understandable. Life is full of dangers and misfortune that plague us at random. Astrology gives us hope that there is a cosmic reason, a connection with the Sun, Moon, and stars that gives order to the apparent chaos we encounter. These emotional needs seem all the more necessary when the heavens behave in ways that aren’t normal, as in an eclipse.

Yet the science of astronomy reveals a far more direct way in which the heavens guide our lives on a daily basis. The Sun gives us light, heat, and food. Those organisms that don’t feed directly on sunlight feed on those organisms that do. Our everyday concepts of position, direction, and time intimately depend upon the motion of that Sun. What is a “day” but a single rotation of our planet? A “year” measures its orbital motion about the Sun while the orbit of the Moon marks the period of time we call a “month.” Imagine every task, chore, rite, or celebration that happens on an annual basis, and you will understand why we needed astronomers in our past. Could civilization have arisen without astronomy? Might we all be the metaphorical descendants of astronomers?

Who were the first astronomers? To answer that question, we must imagine a family tree of our distant ancestors. Four million years ago, our small Australopithecus ancestors first began standing up on the African savanna. As the American astronomer Neil deGrasse Tyson has said, “Once we were standing upright, our eyes were no longer fixated on the ground.” Out in the open, away from the cover of trees, these early ancestors lived under a night sky more vivid than the one we can now see from almost anywhere on Earth. We don’t know if the australopiths noticed, but we do know we are not the only beings on the planet today who notice the sky. Sea turtles, birds, and dung beetles all make use of the stars and the Milky Way in navigation—but we wouldn’t call them astronomers. So our Australopithecus ancestors were not the first astronomers, even if they did something similar. Use alone isn’t science.

By 2.5 million years ago, our Homo habilis ancestors were following animal herds in their annual migrations, and evidence exists for seasonal camps during their travels. Did they plan them by noting the passing of the seasons with the changing Sun and stars in the sky, or did they merely set up new camps as they kept close to the animals they were following? Lions, like our H. habilis ancestors, follow herds, but they aren’t scientists. So perhaps astronomy didn’t begin here, either.

A million years later, our Homo erectus forebears mastered fire, which for the first time extended the day’s work into darkness. Perhaps the first constellations were imagined during those nights, but if so, we have no record of them.

Only 60,000 to 100,000 years ago, the first Homo sapiens fed on shellfish from tide pools on the south coast of Africa. The tides were tied to the Moon and changed each day, both in time and size, as the Moon went through its phases. That’s still the case, of course. And for the early members of H. sapiens, there would have been a benefit to understanding these patterns: those who did would have been able to feed themselves and their families a more varied diet than those who did not. So one might conclude that this is where astronomy began.

But consider for a moment what is required to make the mental connections needed for astronomy. The ocean tide is a direct physical effect; it gets you wet when it rises and reveals its food when it recedes. The Moon, by contrast, is so far away you can’t touch it, hear it, or smell it. There’s no reason, intuitively, that the tides and the Moon should be connected, and what connection there is can only be revealed through observations over a long period of time, requiring memory, abstract pattern recognition, and a belief in an underlying order or relationship.

The archaeologist Steven Mithen referred to these skills as “cognitive fluidity”: the ability to synthesize different forms of intelligence (such as knowing how to build fires, make tools and weapons, and interact in a group and structured society) and to combine these in ways that incorporate abstract ideas, myths, and long-term observations. Evidence for this fluidity appears only after about 60,000 years ago. It is evidenced in the first examples of representational art and in some bone artifacts. If this is the earliest time when something resembling science could have arisen, then the first, most unambiguous evidence of human astronomical knowledge should be more recent still.

Less than a mile from the Nile River, in what was once ancient Nubia, there is a complex of graves. Here, in 1964, archaeologists discovered fifty-eight ancient skeletons all buried on their left sides, facing south, with their heads to the east, toward the rising Sun. “The burial positions,” an astronomer wrote in 2000, were “remarkably uniform,” making it unlikely to be coincidence. The simple fact that the skeletons point eastward means that between 12,000 and 14,000 years ago, someone knew how to identify one of the four cardinal directions. These directions are defined by the sky. The east is where the Sun rises, the west where it sets. The line joining north to south is where the Sun is at its highest during the day, and at night (at least in the Northern Hemisphere), north is the direction around which all the stars turn. Here in the Nubian Desert is actual evidence of astronomical knowledge and of its association with some abstract, intangible meaning.

When one first asks the question, “Why does the Sun rise in the east?” there are two paths to follow for an answer. One path leads to science, the other to religion. For most of human history these paths ran side by side and were often indistinguishable. The ancient answer, “Because the gods make it so,” covers a lot of phenomena and is difficult to refute. This is what we see in the stories of eclipses. Demons and deities eat the Sun and the Moon and do so for reasons known only to them.

This is a tricky path to follow, because any phenomenon we don’t understand can always be blamed on the gods or a god. Why does the Sun rise in the east and not fall from the sky? It’s the work of Apollo and his gleaming chariot. Why do the Sun, Moon, and stars circle overhead? Because God has placed the Earth at the center of the universe around which all things move. In recent years, this same kind of reasoning has been extended to biological evolution by those who believe the process is too complex to have occurred without an Intelligent Designer.


  • One of Amazon's Best Science Books of 2016
  • "Tyler Nordgren's Sun Moon Earth: The History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets is a charming and informative primer on the subject.... As the title suggests, the book is more than a generic guide to next year's is a philosophical, historical, and speculative meditation on the roots of scientific thinking and the development of astronomical theory and practice."—Wall Street Journal
  • "[A] sprightly, informative new guide to solar eclipses..."

  • "Few books have been as valuable to eclipse chasers as this one. In Sun Moon Earth: The History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets, astronomer Tyler Nordgren delivers a comprehensive history of the science and cultural fascination with these almost magical events... It is a niftily written narrative that will entertain, inform, and get your juices flowing for next year's big event."—
  • "When the moon clips our view of the sun or our own shadow blots out our satellite, we experience it with the benefit of millennia of knowledge. We know years in advance when an eclipse will happen, where on the planet it will be visible and, perhaps most importantly, that the world will not end because of it. Our ancestors were not so well-prepared. Astronomer and physicist Nordgren charts the path our species has taken from terror to scientific understanding, and he's done it with and clarity."—Discover
  • "Tyler Nordgren's book takes you on a journey of discovery by telling the tales of astronomers who sailed the world to witness and measure eclipses--and the fierce arguments that shaped scientific theory. Nordgren, an astronomer himself, carefully explains some of the most awesome astronomical discoveries with a clarity that anyone can understand. It covers everything from Christopher Columbus to modern-day methods of measuring transit stars. With a huge solar eclipse set to cover the U.S. in 2017, now would be a good time to bone up on your space knowledge."—Popular Mechanics
  • "On 21 August 2017, the United States will experience its first total solar eclipse in 40 years. Astronomer Tyler Nordgren's primer maps essentials for that event, contextualized by a fascinating history that sweeps us from Anaxagoras' explanation of eclipses in the fifth century BC to Arthur Eddington's test of Einstein's theory of general relativity during the May 1919 total eclipse. Nordgren is a wonderful guide to both the science and the sensory thrills."—Nature
  • "Nordgren, an astronomer at the University of Redlands in California, has spent a lifetime explaining solar-system geometry to people who rarely contemplate their place in the universe. His experience with clarity makes this the best general-interest entry point."—Dallas Morning News
  • On Sale
    Sep 13, 2016
    Page Count
    264 pages
    Basic Books

    Tyler Nordgren

    About the Author

    Tyler Nordgren is an astronomer and Associate Professor of Physics at the University of Redlands. He earned a PhD in astronomy from Cornell University and has worked as an astronomer at both the U.S. Naval Observatory and Lowell Observatory.

    In 2004, NASA’s Spirit and Opportunity rovers landed on Mars carrying sundials, or “Marsdials,” which he helped design as part of a team of seven other scientists and artists. Since 2007, Nordgren has worked closely with the U.S. National Park Service, traveling the country giving public talks, promoting his books, and helping train rangers to provide astronomy outreach in the parks. He lives in Claremont, California.

    Learn more about this author