News | June 19, 1993
Astronomers Solve Ancient Mystery of the Chinese Calendar
Astronomers from the Jet Propulsion Laboratory and the U.S. Naval Observatory have solved the ancient mystery of the origin of the Chinese calendar, it was reported to the 182nd meeting of the American Astronomical Society today in Berkeley, Calif.
Kevin Pang of JPL and John Bangert of the Naval Observatory said they have found a date in 1953 B.C. when the sun, moon and five planets all lined up in the sky at dawn -- providing the basis for the beginning of the Chinese calendar.
The astronomers used planetary positions in ancient times -- available in JPL's ephemerides, or database of planetary motions -- to pinpoint the date.
"Humans have always regarded such rare celestial encounters with awe and foreboding," Pang said. "Recent planetary conjunctions have simultaneously raised hopes for the dawning of the Age of Aquarius and portents for the world's apocalyptic
end," he said.
Although alignments of Jupiter, Mars and other planets have been followed by neither, that has not discouraged new speculations about a coming conjunction of the sun, moon and five planets in the constellation Aries on May 5, 2000 A.D., Pang said.
Pang suggests that westerners' fear of such heavenly signs may have been ingrained by the 1345 A.D. planetary conjunction in the constellation Aquarius, which was followed by the Black Death that killed a third of Europe's population.
In contrast, he said, Asian cultures have always considered a five-planet alignment as a favorable omen, signaling the dawn of
a new age and the world's renewal.
While the beginning of a day is dawn, a five-planet conjunction occurring at dawn, with a new moon, and the start of spring would truly be the beginning of all cycles, he said. For calendar makers, such a moment would also be an ideal starting point for counting days, months, years and planetary periods.
"From the 13th century B.C. they looked for that moment," Pang said. "The quest motivated the ancient Chinese to build ever better clocks, better instruments and observatories. They had a vast network of observers. They finally concluded that such a magic moment never did occur and ended the search in 1280 A.D."
Later, Jesuit missionaries in China, using formulas based on Johann Kepler's laws of planetary motion, took up the search again but they also failed, Pang said.
The date they suggested for the magic moment, February 28, 2449 B.C. is incorrect, yet is still listed in a Guinness book of
In the latest search for the Holy Grail of Chinese astronomy, Pang and Bangert were aided by computer-generated planetary ephemerides and a clue from an ancient text.
Pang found a passage in a 1st century B.C. text of Hong Fan Zhuan, that says: "The Ancient Zhuanxu calendar (invented in about 2000 B.C.) began at dawn, in the beginning of spring, when the sun, new moon and five planets gathered in the constellation Yingshi (Pegasus.)" The book was written by Liu Xiang who lived from 77 to 9 B.C.
Pang said this was all the hint he and Bangert needed. A computer search of planetary positions in the 2000 B.C. era gave
only one possible match -- March 5, 1953 B.C.
Before dawn on that day, Mercury, Venus, Mars, Jupiter and Saturn lined up like a pearl necklace in the eastern sky, next to the Great Pegasus Square, he said. The planets all spanned but a few degrees. The new moon occurred shortly thereafter when the sun, moon, and five planets all lined up in Pegasus, exactly as Liu had stated.
The dawn of March 5, 1953 B.C. was indeed the beginning of a day, month, year and all known planetary cycles, the magic moment Chinese and Jesuit astronomers searched for over 2000 years, Pang said.
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