planetary gravitational field

例句：

1. 1. The planetary nebula is a fascinating sight to behold.
   行星状星云是一个令人着迷的景象。
2. 2.The planetary scientists have been studying the effects of gravity on space objects.
   行星科学家们一直在研究重力对太空物体的影响。
3. 3.The planetary system consists of eight planets orbiting around the sun.
   这个行星系统由八大行星围绕太阳运行。