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.
Zhang Heng observed and recorded 2,500 stars, created the world's first leaky ball that can accurately perform astronomical phenomena, the first instrument to test earthquakes-the waiting wind seismograph, and also made a South Locomotive, an automatic drum car, a wooden bird flying to Wan Li and so on.
Zhang Heng is the author of 32 scientific, philosophical and literary works, among which astronomical works include Lingxian and Lingxian Map.
In order to commemorate Zhang Heng's achievements, people named the crater on the back of the moon as "Zhang Heng Crater" and the asteroid 1802 as "Zhang Heng Asteroid".
Guo Moruo, a famous writer and historian in China in the 20th century, commented on Zhang Heng: "Such an all-round development figure is rare in world history, and it has been admirable for thousands of years."
Later people called Zhang Heng a wooden saint. Zhang Hengzi Hirako. Nanyang County (now Nanyang, Henan Province) is a native of Xi 'e County. Born in the third year of the Eastern Han Dynasty (AD 78); Yonghe died in the fourth year (AD 139). Astronomy, mechanical technology, seismology.