Once Earth had gone through the final stages of its formation, gases bubbled to the surface and were held by Earth's gravitationalfield to form the atmosphere.
一旦地球经历了其形成的最后阶段,气体就会鼓泡到地表,并被地球的重力场控制,形成大气。
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Earth has avoided such an event since in part because of Jupiter's gravitationalfield which limits our exposure to space rocks.
The most sophisticated Earth observation satellite will launch next week to map our planet's gravitationalfield with unprecedented resolution and accuracy.