It was created by a catastrophic collision between our planet and a Mars-size body over 4 billion years ago.

4亿年前，一个火星大小的天体和地球发生了灾难性的碰撞从而产生了月亮。

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Based on current theories of planetary evolution, any extraterrestrials observing the solar system 4 billion years ago would have seen oceans on Venus, Earth, and Mars.

基于现在星球进化的理论，四十亿年前任何外星人观察太阳系都会发现在金星，地球和火星上有海洋存在。

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Researchers had previously thought that there was water - and possibly life on Mars - around 3.8 to 4 billion years ago.

研究人员以前曾经认为，在约38亿至40亿年前，火星上有过水，可能还有过生命。

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Our mission, as it's planned, is to fly over some of the oldest terrain on Mars, very highly magnetized crustal material that dates back to the beginning of Mars, 4.6 billion years ago.

NPR: Revisiting the Viking Missions to Mars

We believe that in its early history - remember, Earth and Mars, the solar system, 4.6 billion years old. 4.6 billion years old the age of Earth and Mars and the solar system.

NPR: Revisiting the Viking Missions to Mars

Mars said it receives a 4-to-1 return on investment for its Nascar sponsorship.

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