黄道是天穹中太阳、月亮和行星运行的轨迹带。
The zodiac is the band around the sky where the sun, moon and planets move through.
他们提到的引力关键点是天文上的一个精确地带，仅仅微大于小行星本身，在那个点上地球引力的影响可以改变小行星运行的轨迹。
The gravitational keyhole they mention is a precise region in space, only slightly larger than the asteroid itself, in which the effect of Earth's gravity is such that it could tweak Apophis' path.
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.
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