Zhang Heng (78- 139) was born in Hirako. Han nationality, a native of Xi 'e, Nanyang (now Shiqiao, Nanyang City, Henan Province), is one of the five saints in Nanyang, and is also known as the four masters of Han Fu with Sima Xiangru, Yang Xiong and Ban Gu. China was a great astronomer, mathematician, inventor, geographer and writer in the Eastern Han Dynasty. He successively served as Langzhong, Taishiling, Shizhong and Hejian.
Rolling loves to think since he was a child, and he always wants to get to the bottom of everything around him. One summer night, Zhang Heng, grandpa and grandma were enjoying the cool in the yard. He sat on the bamboo bed, upturned his head, looked blankly at the sky, raised his fingers from time to time and counted the stars carefully.
Zhang Heng said to grandpa, I counted for a long time and saw that some stars moved, and all the stars that were originally in the east of the sky tilted to the west. Some stars appeared and some disappeared. Aren't they running? Grandpa said: the stars can move. If you want to know the stars, you must look at the Big Dipper first.
That night, Zhang Heng couldn't sleep and got up several times to watch the Big Dipper. He was very happy when he saw the spoon-shaped Big Dipper upside down! I thought: Why does the Big Dipper turn like this? What is the reason? At dawn, he hurried to ask grandpa, who couldn't explain it clearly. So, with this question, he went to read astronomical literature.
Later, when Zhang Heng grew up, the emperor learned that he was outstanding in literary talent, so he called Zhang Heng to Luoyang, the capital, as an imperial adviser, mainly in charge of astronomical calendars. He founded the Huntian theory and made the Huntian instrument according to it. This big copper ball is mounted on an inclined shaft, and it rotates by water power. Its rotation speed is exactly the same as that of the earth.
Zhang Heng grew from a child who counted the stars in the sky to a famous scientist in history. He boldly pursued his goals, was not bound by other worldly fame and fortune, took interest as a teacher, devoted himself to science, and eventually became a generation.
In astronomy, Zhang Heng has written Lingxian and Hunyi Illustration. In mathematics, he wrote The Analects of Confucius, and his literary works are represented by Erjing Fu and Guitian Fu. There is Zhang Hengji (14) in the capital city of Sui Shu, which has been lost for a long time. Zhang Qian, an Amin, compiled the Collection of Zhang He's Bamboo Slips, which was included in the Records of Han, Wei and Six Dynasties 130.
Zhang Heng is one of the representatives of Huntian theory in the middle of Eastern Han Dynasty. He pointed out that the moon itself does not shine, and moonlight is actually a reflection of the sun's light; He also correctly explained the cause of the solar eclipse and realized the infinity of the universe and the relationship between the speed of planetary motion and the distance from the earth. This was not only a great achievement at that time, but also today.