接着开普勒证明了这个椭圆轨道也能很有效解释其他行星的运行轨迹。 然后他提出了行星运动定律，牛顿定律就是以此为理论基础的。
Kepler went on to show that an elliptical orbit is sufficient to explain the movement of the other planets and to devise the laws of planetary motion that Newton built on.
小行星是由岩石或是金属块构成的小天体，他们绕太阳运动但绝不会卷入其他行星的运行轨道中。
Asteroids are stray chunks of rocky or metallic materials that orbit the sun but were never drawn into any of the planets.
机车车辆在轨道上运行是一个动力学过程，也是一个运动学过程。
It is not only a dynamical, but also a kinematical procedure that vehicle runs on the track.
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