行星

• Planets revolve about the sun and rotate on their axis .
  行星在围绕太阳旋转的同时，也绕着它们的自转轴自转。
• Venus, earth, and other planets also perturb mercury's motion .
  金星，地球和其他行星也使水星的运动受到摄动。
• We don't require additional knowledge as to which of the planets is older .
  我们无需再知道哪一颗行星更老些。
• Rather, we infer that planetary systems must be quite common .
  相反，我们的结论是行星系统的存在一定相当普遍。
• Much of the sunlight bombarding the planet is absorbed by the oceans .
  海洋吸收了射到这颗行星上的大部分阳光。
• The peaceful evolution of the protoplanets reached a more dramatic phase .
  平静的原行星进化到富有戏剧性的状态。
• Step edges that are parallel to the planet radius are coated symmetrically .
  与行星径向平行的台阶边缘被对称淀积。
• Planets, asteroids, and satellites shine only by reflected sunlight .
  行星、小行星和卫星都是靠反射太阳光而发光的。
• Planetary perturbations make the earth's orbit about the sun irregular .
  行星的摄动使得地球绕太阳的轨道是不规则的。
• While the protoplanets were coming into existence the sun was still dark .
  当原行星刚刚形成时，太阳还是暗淡无光的。