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Discovering the Universe

The history of Chinese astronomy is one that looks to the heavens, tinkers with bronze inventions and names a comet 'Purple Mountain'


Discovering the Universe

The history of Chinese astronomy is one that looks to the heavens, tinkers with bronze inventions and names a comet 'Purple Mountain'


When you wish upon a meteor, your dream may come true. Such a phenomenon dates back to the Confucian era, when the ancient text Ch’un-ch’iu (Spring and Autumn Annals) observed that “five stones fell in Sung [a state].” Since then, meteor showers have kept coming to China – 300 of them, including the several hundred pieces of rock that fell on Qinghai Province in February 2012.

And if we fast forward to last week, Russia and Cuba were pulverized with asteroids. China Daily stressed an urgent need to research asteroids and other near-Earth objects.

With so much excitement, it is no wonder that astronomy is of great importance to China. By looking at the skies in order to measure time and plan social events, the Chinese eventually developed their first astronomical research institution, Purple Mountain Observatory of the Chinese Academy of Sciences. What used to be a practice reserved for farmers and academics is now a hobby to be enjoyed by all.

Two Heavens

The Chinese have been calculating horoscopes and positions of celestial bodies since the Xia (夏) dynasty (23-17c B.C.). According to the “Canon of Yao” in the Book of Documents (书经 Shujing), a king ordered his brothers Xi (羲) and Hé (和) “to conform themselves to august heaven, to calculate and plot the sun, the moon, the stars and the celestial bodies and respectfully to submit a calendar for humankind.”

In any case, science played a role, too, because of China’s many farmers. They looked to the skies to determine agricultural and social patterns. There were many terms describing heaven (天 tiān), including its motions/cycles (历象 lìxiāng) and objects in the sky (heavenly bodies, 天文 tiānwén). The Xia created a calendar (夏小正 xiăozhēng) and called measuring the calendar lìfă (历法).

Two branches of “heaven” study soon emerged: astronomy and astrology. Both disciplines influenced themes in Chinese philosophy, such as the Uniformity of Heaven and Man (天人合一 tiānrén héyī) and the Sympathy between Heaven and Man (天人感应  tiānrén gănyìng).

Purple Mountain

There are many historical clues sprinkled around China testifying to an advanced knowledge of astronomy, one of the most visible being the Purple Mountain Observatory. Situated at 267m above sea level, it is located on the third peak of Zĭjīnshān Mountain (紫金山) in Nanjing. While the institution opened in 1928, PMO was given its present name in 1934. Its relics include the 60-cm-caliber reflecting telescope, 20-cm-caliber refracting telescope and meridian transit. There are also many instruments from ancient times, including the armillary sphere, abridged “armilla” and gnomon:


Armillary Sphere

Zhang Heng designed the armillary sphere during the Eastern Han Dynasty (25-220). Astronomers used its three nested rings to calculate the positions of the stars. The sphere is also a piece of art, with dragons intertwined on four poles and nature designs carved at the base. Although German troops moved the sphere to Berlin in the 1900s, they returned it to China in 1920.

pmo-astronomy2 Abridged Armilla

Guo Shoujing simplified the armillary sphere during the Yuan Dynasty (1271-1368). His version lets the rings approximate the equatorial ecliptic and horizontal coordinates of celestial bodies separately from one another. He also included a sun dial. Although the Allies looted the area in 1900, the abridged armilla returned to PMO in 1905.



The gnomon is one of China’s earliest inventions, dating back 3,000 years to the Yin-Zhou dynasties. A horizontal slab of rock casted a shadow on its horizontal counterpart, measuring solstices and hours.

All of these instruments led to the discovery of the 365.25-day solar year by the Chinese.


Observing Today

While the PMO heralds many past achievements, it is still an active observatory today. A dedicated team of 281 staff members work at PMO, fulfilling their duties as scientific/technical workers, academics, research fellows and engineers. They have access to the largest astronomical library in East Asia and publish Acta Astronomica Sinica and Chinese Astronomy and Astrophysics. PMO classifies its research into four distinct areas (briefly): interstellar molecular clouds and star formation, solar activity and space weather, astrophysics and basic theory and dynamics of celestial bodies. Discoveries include periodic and non-periodic comets, stars and asteroids (i.e. 3494 Purple Mountain). The first comet given a Chinese surname (Ge Wang) was also discovered there.

Despite such academia, PMO is very popular among tourists. It is a site with a lot of land (i.e. 503.8 sq. m at “headquarters” alone) and a total investment worth over 19 million yuan. Visitors who have the endurance to hike up the mountain (or splurge about 2 kuai to take the bus), can check out PMO’s many sites: an old military fort, the first museum on the history of astronomy in China and the instruments and telescopes.

With the New Year upon us, now is a great time to be reflective and explore the universe at the Purple Mountain Observatory.


Photo of gnomon courtesy of Quinn Baron.