29
See also: Shifting stars 22 ■ Improved instruments 30–31 ■ Zu Chongzhi (Directory) 334
FROM MYTH TO SCIENCE
The two men traveled widely,
setting up another 26 observatories
across China. In 1279, the pair
announced that there were
29.530593 days to a month, and
that the true solar year was
365.2524 days long (365 days,
5 hours, 49 minutes, and 12
seconds). This is just 26 seconds
longer than the current accepted
measurement. Again, China was
ahead of the West. The same figure
was not independently measured
and adopted for the universal
Gregorian calendar in Europe
until 300 years later.
Enduring calendar
A great technological innovator,
Guo invented several new
observational devices and made
enhancements to the Persian
equipment that had begun to
arrive in China under Kublai
Khan’s rule. Most importantly, he
built a giant gnomon to a height
of 44 ft (13.3 m), which was five
times taller than the previous
Persian design and featured a
horizontal crossbar marked with
measurements. This allowed Guo
to measure the angle of the sun
with far greater accuracy.
The Shoushi calendar was
widely regarded as the most
accurate calendar in the world
at the time. As a testament to its
success, it continued to be used
for 363 years, making it the longest-Guo Shoujing Guo Shoujing was born into a poor
family in the north of China, in the
years when the Mongols were
consolidating their control over
the region. A child prodigy who
had built a highly advanced water
clock by the age of 14, Guo was
taught mathematics, astronomy,
and hydraulics by his grandfather.
He became an engineer, working
for the emperor’s chief architect
Liu Bingzhong. In the late 1250s,
Kublai Khan took the throne
and chose the region around the
town of Dadu near the Yellow
River to build the new capital of
Khanbaliq, now known as Beijing.Guo was tasked with building
a canal to bring spring water
from the mountains to the new
city. In the 1290s, Guo—by now
the khan’s chief science and
engineering adviser—connected
Khanbaliq to the ancient Grand
Canal system that linked to
the Yangtze and other major
rivers. In addition to continuing
his astronomical work, Guo
oversaw similar irrigation and
canal projects across China, and
his theoretical and technological
innovations continued to
influence Chinese society
for centuries after his death.To measure the
length of the year, better
instruments must
be created.There is a need to
create a new calendar
that matches the
solar year.The calendar has 365 days and
6 hours in the year, but does not match the
motion of the sun through the year.The solar year is found to be 365 days, 5 hours,
49 minutes, and 12 seconds. There is a
new calendar for China.serving official calendar in Chinese
history. China officially adopted the
Gregorian calendar in 1912, but the
traditional calendar, today known
as the rural or former calendar, still
plays a role in Chinese culture,
determining the most propitious
dates to hold weddings, family
celebrations, and public holidays. ■