The gnomon in the middle is perpendicular to the plate, parallel to the earth's axis, and points to the celestial North Pole (near the north Star).
晷针垂直于晷盘，平行于地轴，指向天北极(北极星附近)。
2
N-body problem is a problem researching on the universal gravitation between celestial bodies, this problem belong to the category of parallel calculation.
体问题是研究天体间万有引力的问题，属于易并行计算的范畴。
3
N-body problem is a problem researching on the universal gravitation between celestial bodies, this problem belong to the category of parallel calculation.