Other Ancient Astronomers

Other Ancient Astronomy

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This page is devoted to the Chinese, Meso-Americans, and Polynesians.

The Chinese have been observing the sky for several millennia, making them the oldest civilization with a continuous astronomical record. The Chinese required that their astronomers were correctly able to predict astronomical events, such as eclipses; otherwise, they were executed.

Charting and Recording

Some of the amazing records that the Chinese hold is the first documented solar eclipse - over 4000 years ago in 2137 B.C. The first recording of any planetary grouping was made by the Chinese in 500 B.C.

Comet Halley In the fifth century B.C., the Chinese made the Book of Silk, the earliest known atlas of comets. It contains 29 comets, which is a collective history of about 300 years. They were referred to as "broom stars." The book was discovered in a tomb in 1973.

The astronomers noted the date, type, constellation in which it was first observed, motion, color, apparent length, and duration in the sky of the comets. They were the first to discover that comet tails always point away from the sun.

Dating to about the same time as the first recorded solar eclipse is the Jiangjunva rock carving. It has symbolic material, but also it contains Sun images in seasonal aspects, the Milky Way, and the moon.

The Chinese constellations were in the form of Five Palaces; the number five possibly results from the five elements of earth, fire, water, metal, and wood.

The Palace of Purple Tenuity was the circumpolar area.
The Palace of the East was the Azure Dragon.
The Palace of the South was the Vermillion Bird.
The Palace of the West was the White Tiger.
The Palace of the North was the Dark Warrior, represented by an intertwined turtle and snake.

The sky was also divided into Nine Fields, which involved the circumpolar region and eight other divisions. The eight other divisions can be related to eight hexagrams which appear in the Yi Jing (The Book of Changes), which dates from the 2^nd century B.C.

There were also the Jupiter Stations, which involved dividing the zodiac into 12 areas along the ecliptic. The 12 divisions were not related to the zodiac developed by the Babylonians and used today, but rather to the 12 years it takes Jupiter to return to the same place among the stars.

Yet another type of sky division were the Lunar Mansions, which goes back to at least the 5^th century B.C. It involves 28 divisions, based upon the lunar sidereal period being 27.32 days. This was of particular importance in astrology.

The Chinese divided the celestial equator into 365.25° - the daily average motion of the sun. This corresponds to our current charting technique of Right Ascension (RA, α). They used similar degrees north and south of the equator, equivalent to our current Declination (DEC, δ). This is in sharp contrast with western cultures, who didn't use modern positioning systems until the late 1500s.

As far as cataloguing went, Shi Shen, Gan De, and Wu Xian (370-270 B.C. in sum) recorded 1464 stars in 284 constellations. This is 200 years before the first western catalogue (by Hipparchus). In A.D. 310, Astronomer Royal Qian Luozhi had a bronze celestial globe made with stars that were color-coded as to their source. From the Han Dynasty, there are carvings that show constellations and asterisms with stars linked to delineate the various groups.

For charts, the earliest known dates to around A.D. 700. Though it has no grid lines, it contains over 1350 stars, and is a flat version of the Qian Luozhi globe. Nearly 400 years later, in A.D. 1094, the Song Dynasty created star charts. They show coordinates and were prepared for use with an "armillary sphere" - a sphere that consists of a number of rings arranged so as to model the circles of the celestial sphere. Until the Renaissance, these were the most accurate star charts available.

Observational Instruments and Resulting Measurements

The "gnomon" was a vertical stick in the ground. It could be used to determine the local noon and the seasons via the summer and winter solstices and the spring and fall equinoxes. They were standardized throughout the Chinese empire to be 8 "chi" or 2.4 meters.

The largest gnomon was built by Gui Shou-jing in A.D. 1276. It was 12 m high; its large size was influenced by the Arabs, who demonstrated that a larger instrument is more precise.

Through use of the gnomon, the Chinese determined the circumference of the Earth. Between A.D. 721-725, several sites in Hue, Vietnam to Lingqui, China (near the Great Wall), were selected in a nearly straight North-South line. Their result was that 1° of latitude was 155 km, where the actual value is about 111 km. The Greeks were able to get this to a much more accurate measurement around 300 B.C.

Predicting

Astronomers were attached to the royal household as second tier functionaries. Study of astronomy outside of this position was strongly discouraged for security reasons. This stemmed from the belief that the night sky predicted Earth-bound events and moods, such as whether the gods were happy with the current emperor. As a side note, astronomers were also in control of the water clocks.

One of the most important events to predict were eclipses. In the first century B.C. (the Han dynasty), an eclipse period of 135 months was recognized during which 23 eclipses were known. By the third century A.D., the astronomer Yang Wei was able to specify times of first contact for a solar eclipse.

Precession

Hipparchus is credited with discovering precession around 150 B.C., and it took Chinese astronomers another 400 years to recognize it around A.D. 330. Even then, though, they did not recognize it as a continuous phenomenon, and it was called an "annual difference."

This section, though including all Central and South Americans, is mostly attributed to the Mayans. The main accomplishments were an elaborate calendar, many glyphs that appear to be priests taking horizon sightings, planets glyphs (especially Venus), architectural alignments, and written materials such as eclipse records and Venus tables.

After they had developed a concept of numerical places and zero, they were able to develop a zodiac, mars tables which included retrograde motion, an eclipse warning table, and a calendar based upon Venus.

Celestial objects that were observed were Tonatiuh (Sun), Mextli (Moon), solar and lunar eclipses, Tianquiztli (Pleiades), Citlalpol (Venus), Cilalpopoca (comet), Citaltamina (meteors), Xonecuilli (Little Dipper), and several objects which are not currently confirmed. Those falling into this last category include Mamalhuaztli, the Fire Drill (Orion?), Citlaltlachtli (Gemini?), and Citlalcolotl (Scorpio?).

The Polynesian islanders were among the first people to navigate the oceans, and they used the stars to guide them. The sun marked their day, but very strict records of stars were kept in order to guide them during the night; this practice started before the dawn of the Christian era -- over 2000 years ago.

Often, the way they would keep track of stars was by creating mythologies around them, much as the Greeks did. For example, the Pleiades (an open cluster), Jupiter, and Aldebaran (a bright red star), are central to the founding story of the polynesian culture.

By using fixed locations on the horizon, sailors memorized hundreds of stars and were able to determine their longitude and latitude to a high accuracy. By memorizing the positions, brightness, colors, and time of year that stars were visible, sailors were equipped to navigate at any time during the year.