Zhang Sixun, a native of Shicheng, Enyang district, Bazhong city, Sichuan province, was a famous astronomer in the Northern Song Dynasty (960-1127). He was diligent and studious as a child, and was keen on astronomical observation.

After repeated trials and improvements, Zhang made major innovations in producing armillary spheres. In 979 AD, he manufactured the world's first automatic planetarium, the Taiping Armillary Sphere.

This instrument is powered by mercury, and it was the first of its kind among the world's mechanical instruments that used mercury. The Taiping Armillary Sphere defined and standardized a series of astronomically-based phenomena, including seasons, solar terms, time and temperature differences, years, months, days and hours for the first time. It had epoch-making significance and helped astronomy be recognized as a scientific and rational subject.