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授时历 The Season-Granting Calendar - Calendar genius' date with history
October 28, 2012, Sunday
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Print Edition
Print Edition
INTRODUCED in 1281, Shoushi Calendar, or the Season-Granting Calendar, has widely been deemed the most accurate calendar at its time both in China and the world.
The Shoushi Calendar determined that the length of the tropical year was 365.2425 days - only 26 seconds off the current measurement of the year and the same as that determined by the Gregorian Calendar, but it was obtained more than 300 years earlier.
The calendar was compiled by famous astronomer, engineer and mathematician Guo Shoujing (1231-1316), together with his colleague Wang Xun and others.
China boasts a long history of producing and using its own calendars, with its first calendar dating back to the Warring States Period (475-221 BC).
Unlike the Gregorian Calendar, which is a solar calendar and follows the movement of the sun, Chinese calendars are either lunisolar or lunar calendars, which follow the actual movement of the moon.
As a result, while the Gregorian Calendar defines the leap year by inserting a day into the second month, Chinese calendars insert a leap month into the year to keep themselves in tune with the movement of the sun.
Also, Chinese calendars feature 24 fortnightly solar terms, such as Start of Spring, Awakening of Insects, Vernal Equinox, Grain Rain, Limit of Heat, Frost Descent and Winter Solstice. These were designed to describe specific astronomical and natural phenomena and guide farmers.
Meanwhile, emperors of Chinese dynasties also paid great attention to the formulation and use of calendars since they always wanted to know various astronomical occurrences so they could make important decisions and conduct imperial events and ceremonies according to these "heavenly" phenomena.
Kublai Khan, the first emperor of the Yuan Dynasty (1271-1368), was no exception. After consolidating his power as a new emperor in China, the grandson of the Mongol Empire founder Genghis Khan ordered a group of famous astronomers, including Guo Shoujing, to make a more accurate calendar.
This was partly because the previous dominant calendar, the Daming Calendar, created by Zu Chongzhi (AD 429-500), a prominent Chinese mathematician and astronomer, was already more than 700 years old and badly needed revision.
To obtain accurate and thorough observations for calculations, Guo and his team asked the emperor to build 27 observatories across the country, with the northernmost located at Tiele near the Yenisei River in today's Siberia in northeastern Asia. The southernmost was established on Xisha Islands in today's South China Sea. The observatories spanned several thousand kilometers.
In addition, Guo had renovated and invented more than a dozen astronomical instruments to generate more accurate data. One of them was the gnomon, a stick erected for the purpose of measuring its shadow. Its minimum shadow length would change, from lengthening to shortening on the Winter Solstice, and visa versa on Summer Solstice. Guo added a crossbar on the top of his gnomon and created a scale to ensure precision within 2 millimeters.
To interpret the data, Guo and his team had gathered from those observatories using new instruments, the astronomer also devised some remarkable formulas of spherical trigonometry based on the knowledge existing at that time.
In 1280, formulation of the new calendar was completed and it was put into use for the next 364 years. It was later adopted by Korea and Vietnam.
Today, people in China typically use a calendar combining both the Gregorian Calendar and the traditional Chinese lunar calendar. While most follow the former for their daily work and life, they often check the lunar calendar when making personal decisions and observing traditional rituals, such as picking a wedding day or worshipping their ancestors. TEXTS THAT have SHAPED CHINA Throughout China's long history, classic texts have played a vital role in shaping the country and the everyday lives of its people. They have provided academic learning, practical advice, instruction on how to live and given expression to hopes and dreams, joys and sorrows. In this series, we introduce classic texts, spanning more than 3,000 years, covering everything from science, mathematics and military strategy, through to religion, philosophy and art, literature and travel. Written by Zhang Ciyun, editor-in-chief of Shanghai Daily, these are the stories of China's classic texts, how they made their mark on the country and how their influence can often be felt to this day.
The Shoushi Calendar determined that the length of the tropical year was 365.2425 days - only 26 seconds off the current measurement of the year and the same as that determined by the Gregorian Calendar, but it was obtained more than 300 years earlier.
The calendar was compiled by famous astronomer, engineer and mathematician Guo Shoujing (1231-1316), together with his colleague Wang Xun and others.
China boasts a long history of producing and using its own calendars, with its first calendar dating back to the Warring States Period (475-221 BC).
Unlike the Gregorian Calendar, which is a solar calendar and follows the movement of the sun, Chinese calendars are either lunisolar or lunar calendars, which follow the actual movement of the moon.
As a result, while the Gregorian Calendar defines the leap year by inserting a day into the second month, Chinese calendars insert a leap month into the year to keep themselves in tune with the movement of the sun.
Also, Chinese calendars feature 24 fortnightly solar terms, such as Start of Spring, Awakening of Insects, Vernal Equinox, Grain Rain, Limit of Heat, Frost Descent and Winter Solstice. These were designed to describe specific astronomical and natural phenomena and guide farmers.
Meanwhile, emperors of Chinese dynasties also paid great attention to the formulation and use of calendars since they always wanted to know various astronomical occurrences so they could make important decisions and conduct imperial events and ceremonies according to these "heavenly" phenomena.
Kublai Khan, the first emperor of the Yuan Dynasty (1271-1368), was no exception. After consolidating his power as a new emperor in China, the grandson of the Mongol Empire founder Genghis Khan ordered a group of famous astronomers, including Guo Shoujing, to make a more accurate calendar.
This was partly because the previous dominant calendar, the Daming Calendar, created by Zu Chongzhi (AD 429-500), a prominent Chinese mathematician and astronomer, was already more than 700 years old and badly needed revision.
To obtain accurate and thorough observations for calculations, Guo and his team asked the emperor to build 27 observatories across the country, with the northernmost located at Tiele near the Yenisei River in today's Siberia in northeastern Asia. The southernmost was established on Xisha Islands in today's South China Sea. The observatories spanned several thousand kilometers.
In addition, Guo had renovated and invented more than a dozen astronomical instruments to generate more accurate data. One of them was the gnomon, a stick erected for the purpose of measuring its shadow. Its minimum shadow length would change, from lengthening to shortening on the Winter Solstice, and visa versa on Summer Solstice. Guo added a crossbar on the top of his gnomon and created a scale to ensure precision within 2 millimeters.
To interpret the data, Guo and his team had gathered from those observatories using new instruments, the astronomer also devised some remarkable formulas of spherical trigonometry based on the knowledge existing at that time.
In 1280, formulation of the new calendar was completed and it was put into use for the next 364 years. It was later adopted by Korea and Vietnam.
Today, people in China typically use a calendar combining both the Gregorian Calendar and the traditional Chinese lunar calendar. While most follow the former for their daily work and life, they often check the lunar calendar when making personal decisions and observing traditional rituals, such as picking a wedding day or worshipping their ancestors. TEXTS THAT have SHAPED CHINA Throughout China's long history, classic texts have played a vital role in shaping the country and the everyday lives of its people. They have provided academic learning, practical advice, instruction on how to live and given expression to hopes and dreams, joys and sorrows. In this series, we introduce classic texts, spanning more than 3,000 years, covering everything from science, mathematics and military strategy, through to religion, philosophy and art, literature and travel. Written by Zhang Ciyun, editor-in-chief of Shanghai Daily, these are the stories of China's classic texts, how they made their mark on the country and how their influence can often be felt to this day.
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