轨道

• 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。
• An electron moving in an excited orbit stays there only for a very short time .
  电子在激发态轨道上只能逗留很短的时间。
• Satellite lifetimes in orbit range from a matter of days to hundreds of years .
  卫星在轨道上的寿命从几天到几百年不等。
• Looking to the south, the paths of the stars are simply very large circles .
  往南看，恒星的轨道简直成了一些很大的圆周。
• The launcher and vehicle are then transported to the firing pad by a crawler .
  发射器和飞行器由一个爬行轨道送到点火台。
• Twenty incoming flights were stacked up overhead, and orbiting。
  仍然有二十架已经飞进来的班机积压在上空，在轨道上盘旋。
• The moon doesn't describe a circle round the earth, but rather an ellipse .
  月球绕地球运行的轨道不是浑圆的，而是椭圆的。
• In the space program the theory is used to determine spaceship trajectories .
  在空间计划中，这个理论用于确定飞船的轨道。