极地轨道气象卫星以大致南北方向环绕地球运行。它的轨迹离地面约数百公里。

Polar-orbiting satellites are low-flying satellites circling the earth in a nearly north-south orbit, at several hundred kilometers above the earth.

环绕地球运行的卫星，为科学家提供了浩如烟海的外层空间的资料，相比之下，对地球内部的结构则知之甚微。

Satellites orbiting round the earth have provided scientists with a vast amount of information about conditions in outer space.

或者大规模的小行星或是彗星对地球的撞击将海水溅入太空，环绕地球运行的月球经过这片蒸汽云，出来时就变得湿漉漉了。

Or perhaps catastrophic asteroid or comet impacts on Earth ejected seawater into space, and the orbiting moon passed through the vapor cloud, emerging somewhat soggier .

谁都不曾设想过。不过，根据环绕地球运行的费米卫星在过去的两年收集的数据，我们越来越清晰地看到我们的银河系中心的非比寻常的巨幅特写。

As the data from the Earth-orbiting Fermi satellite began accumulating over the past two years, however, a large and unusual feature toward our Galaxy's center became increasingly evident.