Jade Turtle: When Astronomy Met Astrology

Today, we’ll talk about a 5,000-year-old grave in eastern China and learn about the man with three identities buried inside it: he was an astronomer who measured the solstices with stunning accuracy, a shaman who placed the universe over his own heart, and a warrior who carried a giant stone axe. 

Jade Turtle: When Astronomy Met Astrology

Today, we’ll talk about a 5,000-year-old grave in eastern China and learn about the man with three identities buried inside it: he was an astronomer who measured the solstices with stunning accuracy, a shaman who placed the universe over his own heart, and a warrior who carried a giant stone axe. 

Every year in mid-September, amateur astronomers around the world will set up their telescopes in city squares, schoolyards, and dark fields far from city lights. They will invite both friends and strangers to look through the eyepiece to marvel at the rings of Saturn, the craters on the Moon, or the faint glow of a distant galaxy. September 19 marks International Astronomy Day, which was first launched in 1973 by the Astronomical Association of Northern California and became globally popular over the ensuing decades. Its mission is simple: to take astronomy out of restricted observatories and put it into the hands of stargazing citizens.

And this year on Astronomy Day, we want to ask: What was it like to watch the stars before we understood what we were looking at? How did humanity’s oldest astronomers begin to explain it? And why – for most of human history – was the person who interpreted the patterns in the sky also someone who talked to spirits, performed sacrifices, and claimed to speak for the gods? Today, an astronomer is a scientist. He or she uses calculus, physics, and billiondollar telescopes. But in ancient China, and in most early civilizations, the astronomer in your local village was never only a scientist.

We know this because in 1987 some modern scientists traveled to a muddy field in Anhui Province of eastern China to a grave more than 5,000 years old. At a site called Lingjiatan, archaeologists opened a Neolithic tomb and were astounded by a plethora of astrological symbolism. The skeleton in the tomb lay on its back, and right over its heart – the most intimate place in any burial – were two objects made of pale green jade. One was a turtle, no bigger than a human palm. But this turtle came in two pieces: a domed upper shell and a flat lower shell, each drilled with tiny holes so they could be tied together with cord, forming a hollow container.

The upper shell was rounded like the sky. The lower was square like the Earth. This was the oldest expression of a Chinese idea that would last for millennia: Heaven is round, and Earth is square.

Inside that jade turtle, sandwiched between the two shells, lay a thin rectangular plaque, also jade, carved with extraordinary precision. In the center is an eightpointed star. Around it, two concentric circles divided into eight equal sections. In each section, there’s a tiny rectangular mark shaped like a ruler. Around the edges of the plaque, there are 23 perfectly drilled holes.

Modern scholars have decoded this design. The eightpointed star appears across Neolithic China and represents the division of time and space into eight directions and eight seasons: the solstices, equinoxes, and the four crossquarter days. The rulershaped marks point to a specific technology: gnomon shadow measurement. You stand a pole upright. You measure its shadow at noon. The shortest shadow is summer solstice. The longest is winter solstice. The two middle points are the equinoxes. That is the gui – the measuring ruler. The jade plaque from Lingjiatan is a 5,000yearold scientific instrument, a calendar, and a treatise on astronomy, carved in jade.

But why place this scientific instrument inside a turtle, and why put it over a man’s heart? The answer is ritual. The turtle’s two shells, drilled to be tied together, formed a closed container – a device for holding something secret. The same tomb also yielded a jade stick, pointed at one end, which scholars believe was used to point at the plaque’s symbols during divination. When the shaman shook the turtle, opened it, and “read” the arrangement of the plaque’s marks, he was not doing science. He was doing magic – or rather, one might say, he was doing both at once. By placing the turtle over his heart, the most spiritually charged part of the body, he declared himself the conduit between heaven and earth. If he could predict the solstices, he could thereby interpret the will of the gods. That is what made him a priest.

But the man also wore another hat. Lying next to his head in the tomb was a large stone axe weighing 4.25 kilograms, made of volcanic rock, and polished like a mirror. In ancient China, that axe – called a yue – was both a weapon and a symbol of military authority. The character for “king” in the earliest Chinese writing is a pictograph of an axe. Thus, the man in the grave was three things at once: an astronomer who mastered the calendar, a shaman who placed the universe over his heart, and a warrior who carried a battleaxe. 

This man’s official title today might be something like “minister of heaven”, but he also led armies. A combination of scientist, priest, and general. One person, three identities.

But how is it that these three roles would merge? Scholars explain it this way: In a Neolithic farming society, knowing when to plant and harvest meant the difference between feast and famine. If you could predict the seasons, you could feed your people. And if you could feed your people, you had their loyalty. But loyalty alone is fragile. You also need legitimacy. So, you tell them: this knowledge did not come from me. It came from heaven. The gods revealed it to me. I am their messenger. Then you have to prove it, right? So, you announce that on a certain day, the shadow will be the shortest. It happens. The people are convinced. They bring you gifts. And they ask you to perform rituals.

Now, this fusion of science with “magic” was not unique to China. The Maya of Central America had astronomerpriests who lived in temples/ (slash) observatories. The Babylonians of Western Asia had scribes who recorded planetary motions but also cast horoscopes for kings. The Egyptians aligned pyramids with stars and claimed the pharaoh himself was a celestial being. 

But the people of ancient Greece took a different turn. Around the 6th century BCE, Thales of Miletus predicted an eclipse – not by reading omens, but by using geometry. Anaximander argued that the earth floated unsupported in space. By the 3rd century BCE, Aristarchus had proposed a heliocentric model. Eratosthenes measured the circumference of the Earth with two sticks and a well – no spirits required. 

Greek astronomy did not instantly become secular, but a crucial seed was planted: nature could be understood through reason and observation alone, without priestly mediation. That tradition survived through the Islamic Golden Age – AlBattani refined eclipse calculations, Ibn alHaytham pioneered the scientific method – and eventually helped ignite the Scientific Revolution in Europe.

And yet, even the West was slow to separate science from superstition. As late as the 16th century, Tycho Brahe – the greatest nakedeye observer in history – helped prove that comets were not atmospheric phenomena, yet still regarded them as divine warnings. Johannes Kepler, who discovered the elliptical orbits of planets, also cast horoscopes for his patrons. Isaac Newton wrote more about biblical prophecy and alchemy than about physics. 

The division between astronomer and astrologer was only fully established in the 18th and 19th centuries when rationalism and empirical science finally separated itself from beliefs founded in superstition and pseudo-science. In China, that line took even longer to dissolve – not because Chinese astronomers were less intelligent, but because the imperial state had a much deeper interest in keeping the heavens mysterious.

For over two millennia, China’s imperial court monopolized the field of astronomy. In fact, private study of the heavens could be illegal – sometimes punishable by death. The reason was not ignorance, of course, but as a means to an end – to manage populations – to exact power over those less educated. If just anyone could predict an eclipse, they could claim to know heaven’s will. And if they could read heaven’s will, they could challenge the emperor. So, Chinese astronomers – and no one else – became incredibly skilled at prediction.

As early as the Tang Dynasty, 618 to 907, Chinese astronomers were able to calculate eclipses to within one hour. Later during the Song Dynasty, Chinese astronomers produced the most accurate star maps in the world. Then in the Yuan Dynasty, Scientist Guo Shoujing built advanced gnomon instruments and created a calendar only 26 seconds off the true tropical year. This was worldclass science. But it was science with a chain. Every calculation served the throne. When an eclipse occurred, the emperor had to issue a selfcriticism and perform rituals to “rescue the sun.” The question “why?” was always secondary to “how does this affect the dynasty’s fate?”

The separation of astronomy from astrology in China took centuries. A turning point came in the Song Dynasty with scientist Shen Kuo, who in his Dream Pool Essays described the polar star’s movement and advocated for precise instruments to be employed with no link whatsoever to superstition. 

But the real cosmic epiphany came in the 17th century, when Jesuit missionaries arrived in Beijing. German missionary Johann Adam Schall von Bell brought European astronomy to the Qing court, reformed the calendar using Western methods, and predicted eclipses with unprecedented accuracy. The Kangxi Emperor, fascinated by mathematics, studied Western astronomy himself. He realized that the European approach, with its geometric models and empirical verification, worked better.

The divine aura around Chinese astronomy began to fade. By 1905, the Qing court abolished the imperial examinations and made astronomy a distinct science subject offered at newly established universities. In 1912, the new Republic of China formally abolished the Imperial Astronomical Bureau, which for centuries had been both a scientific agency and a department of sacred divination. The scientist and the shaman finally parted ways.

In this sense, the 5,000yearold jade turtle is not just an artifact. It reflects the deep human need to connect the sky to power, meaning, and legitimacy. The man buried at Lingjiatan was one in a very long line. He was the ancestor of every Chinese astronomer who measured eclipses for the emperor but also cast horoscopes for the court.

This year, on Astronomy Day, we no longer rely on shamans. We have telescopes, satellites, and computers. We know that the Moon is not a god but a giant rock. We know that comets are not bad omens but dirty snowballs. And yet, when we look up on a clear night, we feel stirred by something ancient, something primordial. There’s still a sense of wonder and perhaps a hunger for meaning.

The jade turtle of Lingjiatan now rests in the Palace Museum in Beijing. Its carvings are still sharp, their meanings made clear. And if you stand before it, you can almost hear the voice of the man who once wore it over his heart. He may not understand our telescopes, but he would undoubtedly recognize our questions.

Well, that’s the end of our podcast. Our theme music is by the famous film score composer Roc Chen. We want to thank our writers Zhang Jin and Zhou Fangning, translator Yu Shougang, and copy editor Pu Ren. And thank you for listening. We hope you enjoyed it, and if you did, please tell a friend so they, too, can understand The Context.