1.Mars and Earth have orbits which change with time.
火星和地球的轨道随着时间而发生改变。
2.Astronomers had thought that the orbits of the planets were predictable.
天文学家早就认为，几大行星的轨道是可以预测的。
3.But most orbits won't be.
但大部分轨道不会。
4.It orbits a red dwarf star.
它绕着一颗红矮星运行。
5.They will likely then travel close enough to neighboring planets to disturb their orbits also.
然后，它们很可能会飞得离邻近的行星足够近，从而扰乱它们的轨道。
6.The Earth orbits in an ellipse.
地球沿椭圆形轨道运动。
7.Dr Bottke has been tracking the orbits of asteroids.
伯克(Bottke)博士一直在追踪小行星的运行轨迹。
8.The most complex engineering project ever attempted has created an enormous set of interlinked modules that orbits the planet at more than 27,000 kilometres per hour.
