General Science of the Day
What is a Ganzhi Period? (FAQ for Astronomy)

A Ganzhi period is also called a sexagenary cycle or a Jiazi period. The lunar calendar uses a Ganzhi period to count days as well as years, months, or hours. The 10 heavenly stems of Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui are matched with the 12 earthly branches of Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai in pairs to become the 60 Ganzhis. For instance, the 60 Ganzhis are used to represent 60 days sequentially in continuous cycle. From the inscriptions on bones or tortoise shells it was found that there was a complete day counting system from the beginning of the Shang Dynasty for an uninterrupted period of over three thousand years. This is known to be the oldest method of counting days in the world.

Report on Sunspot Observations
General Info of the Day
Date 2017-10-23
Moon Phase of the Day
Astronomy phenomenon
Sunrise and Sunset, Moonrise and Moonset