Uranus is circled by a blue ring - a colour that makes it almost unique among planetaryrings, which are usually red.
行星光环通常为红色，这使得天王星的蓝色光环显得独树一帜。
2
Work on Uranian rings and some general problems of the planetaryrings including the collision process in the rings, the photometric theory and their origin are also elucidated.
F环。还评述了天王星环以及行星环中的碰撞、光度理论和起源等问题的研究。
3
Secondly, the forces of inner cam rings, planetary bearings, counter weights and input shaft are solved after the acting force between the cam and the rollers has been calculated.