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IS THE EARTH MADE OF TWO PLANETS?

机译：地球是由两颗行星吗?

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The birth of planet Earth came at a chaotic time. Scientists theorize that before Earth was formed 4.5 billion years ago an enormous cloud of gas and dust began coalescing into the planets, moons, and asteroids of our solar system. Among those planets was one called Theia, which collided with Earth about 100 million years after the planets formed. Scientists have known about the crash for a long time, but they assumed that Theia had collided with Earth in a powerful sideswipe (at an angle greater than 45 degrees). However subsequent evidence suggests that the collision was head on and violent. To arrive at the new theory, planetary scientist Edward Young and his team at the University of California, Los Angeles studied volcanic rocks from Earth's mantle and compared them with samples brought back from the Moon by the Apollo missions. Nearly all of Earth's oxygen consists of 0-16 atoms, which comprise eight protons and eight neutrons, but small amounts are atoms of 0-17 and 0-18, which have one or two extra neutrons, respectively. Each of the planets in our solar system has a distinctive ratio of the various oxygen atoms-in other words, a unique chemical fingerprint. Earlier research had suggested that the oxygen fingerprint of the Moon was different from that of Earth, but Young's team found this was not the case at all. "The two sets of oxygen isotopes are indistinguishable from each other," says Young, who teaches geochemistry and cosmochemistry at UCLA. "We don't see a difference between those from the Earth or the Moon." Had Theia collided with Earth in a glancing blow most of the Moon would consist of material from Theia, and the Moon's isotopes would be different from those of Earth. Similar chemical composition, on the other hand, suggests a head-on collision and therefore a common origin for our planet and its satellite. "Theia was thoroughly mixed into both the Earth and the Moon and evenly dispersed," says Young. "And that explains why we don't see a diff
机译：地球的诞生是一个混乱的时候。科学家们推测,在地球形成之前45亿年前,一个巨大的星云和尘埃开始凝聚成行星卫星,和我们的太阳系小行星。这些行星是一个叫忒伊亚与地球相撞后大约1亿年行星的形成。车祸很长一段时间,但他们认为忒伊亚在一个强大的与地球相撞侧击(在一个角度大于45度)。然而随后的证据表明碰撞是和暴力。新理论,行星科学家爱德华年轻和他的团队在加州大学的洛杉矶从地球的洛杉矶研究火山岩地幔和比较样品了从月球的阿波罗计划。地球上所有的氧气由约原子,这包括八个质子和8个中子,但少量原子0 17和0-18有一个或两个额外的中子,分别。系统有着独特的比例不同原子氧——换句话说,一个独特的化学指纹。月亮的氧气指纹是不同的地球的,但年轻的团队发现了这个并非如此。同位素是区别开来。”任教的地球化学和年轻的说加州大学洛杉矶分校的天体化学。这些从地球或之间的区别月亮。”侧击的月亮将包括材料从忒伊亚,月亮的同位素将不同于地球。化学成分,另一方面,建议正面碰撞,因此一个共同的起源为我们的地球和它的卫星。彻底地混合到地球和月球和均匀分散,”年轻人说。解释了为什么我们看不到差异

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