First, "Seven Obsidian Techniques"
The seven nights refer to the sun, the moon and the five planets of "gold, wood, water, fire and earth". The period and operation law of "five-star rendezvous" are calculated accurately. Some data in "Seven Obsidian Techniques" are exactly the same as those calculated by modern high-precision astronomical instruments. Some "differences" are very small. Nearly 2000 years ago, it was difficult to get such accurate astronomical data without profound professional knowledge and perseverance.
Second, the dry calendar
This is the first calendar in the history of our country and even of mankind that takes into account the "non-uniformity of lunar movement". The completion of Dry Phase Calendar is a breakthrough in the calendar history of our country, thus laying the foundation of China's "Moon Movement" theory.
Three, "Nine Chapters Arithmetic Note"
"Nine Chapters Arithmetic Notes" should be a mathematical work that annotates classic mathematical masterpieces of the same name and integrates research experience. Therefore, Liu Hong is famous for his mastery of arithmetic.
Other astronomers in ancient China:
1, Gander
Gander, a native of Qi during the Warring States Period, lived in the middle of the 4th century BC. He was a famous astronomer in the pre-Qin period, the editor of the world's oldest catalog and the earliest discoverer of Ganymede. His works include Tian Wen Star Wars and Sui Xing Jing in eight volumes. Later generations combined it with the astronomical works written by the stone god, and called it "Shi Gan Xing Jing", which is the earliest astronomical work in the world.
2. Shi Shen
In the mid-Warring States period, a Wei astronomer and astrologer born in Kaifeng was one of the China people who named the crater on the back of the moon after him. He has eight volumes of Astronomy (this book was honored as Historical Records after the Western Han Dynasty). Eight Volumes of Astronomy and Eight Volumes of Stars by Gander are collectively called Shigan Star Classic, which occupies an important position in the history of astronomy in China and the world.
Reference to the above content: Baidu Encyclopedia-Liu Hong