planetary cam行星凸轮planetaryadj.行星的；有轨道的planetary transmission(英:epicyclic gearbox)行星齿轮变速器,行星变速器,行星传动planetary scale system行星尺度天气系统planetary rolling mill行星式轧机planetary geared hoist行星齿轮式吊车,行星齿轮传动提升机planetary space flight行星空间飞行planetary perturbation行星摄动planetary ball milling行星球磨planetary ball swaging行星式钢球冲击缩管机planetary gear systems行星齿轮传动planetary rover vehicle深空探测车

1. The orientation of the planet's orbit is changing continuously.
   该行星轨道的方向不断变化。
2. Under proposed International Astronomical Union definitions, two planets that orbit each other around a barycenter between them are a binary planet.
   根据国际天文学会的定义提出两个行星轨道周围的重心在彼此之间是双行星系统。