The direction towards which the Earth’s axis points at a given time. Its path on the sky consists of oscillations due to nutation superimposed on the precessional motion about the pole of the ecliptic.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。