科学家发现地球与其它行星相撞的证据藏在地球深处

Scientists have recognized since the 1970s that there are two large, mysterious blobs in the deepest part of Earth's mantle.
科学家们自20世纪70年代以来就认识到，在地幔最深处有两个巨大而神秘的斑块。

One of the masses is under Africa and the other under the South Pacific Ocean.
其中一块在非洲海底，另一块在南太平洋海底。

Recent research suggests these masses, which are denser than the material surrounding them, might be from a huge crash early in our planet's history.
最近的研究表明，这些比周围物质密度更大的斑块可能来自地球历史早期的一次巨大撞击。

Researchers recently said the crash between Earth and a Mars-sized object called Theia might have created the moon.
研究人员最近表示，地球和火星大小的物体忒伊亚之间的碰撞可能创造出了月球。

Recent research suggests the event happened more than 4.46 billion years ago. Pieces of Theia, however, might have remained inside Earth, sinking to an area just above our planet's hot core of iron and nickel.
最近的研究表明，这一事件发生在44.6亿年前。然而，忒伊亚的碎片可能留在地球内部，下沉到地球炽热的铁镍核心上方的区域。

Researchers created computer simulations to study their theory of the event. Based on these simulations, they proposed that most of Theia was absorbed into Earth, forming the two masses, while the remaining pieces formed the moon.
研究人员创建了计算机模拟实验来研究他们对这一事件的理论。基于这些模拟实验，他们提出忒伊亚的大部分被地球吸收，形成了两个斑块，而其余的部分形成了月球。

Qian Yuan is a geophysicist at Caltech and the lead writer of the study that was published recently in Nature.
钱源（音译）是加州理工学院的地球物理学家，也是最近发表在《自然》杂志上的这项研究的主要作者。

"The bottoms of these blobs are 2,900 kilometers below our feet. The two blobs are about 2 percent of Earth's mass. They were detected by seismology as seismic waves travel slower within these two regions compared to the surrounding mantle. Each of the blobs are twice the mass of the whole moon. So, the blobs are massive," Yuan said.
钱源说：“这些斑块的底部在我们脚下2900公里处。这两个斑块的质量约为地球质量的2%。它们是由地震学探测到的，因为地震波在这两个区域内的传播速度比周围的地幔慢。每个斑块的质量都是整个月球的两倍。所以，这些斑块非常巨大。”

If the theory is correct, these two masses would represent evidence of the possible moon-forming crash.
如果理论是正确的，这两个斑块将代表可能形成月球的碰撞的证据。

Caltech professor and study co-writer Paul Asimow said there has not been agreement "on whether we can find evidence for this event not just in the moon but also in some observable property of the modern Earth."
加州理工学院教授、该研究的合著者保罗·阿西莫表示，“我们是否不仅能在月球上，还能在现代地球的一些可观测特性中找到这一事件的证据，目前还没有达成一致。”

The two masses, Asimow added, are the biggest difference "in Earth structure from a simple layered planet."
阿西莫补充道，这两个斑块是“地球结构与简单层状行星的最大区别”。

study co-writer Hongping Deng of the Chinese Academy of Sciences' Shanghai Astronomical Observatory said, "It is incredible because we can uncover relics of another planet - Theia - if we dig deep enough in Earth's mantle."
该研究的合著者、中国科学院上海天文台的邓宏平说：“这太不可思议了，因为如果我们在地幔中挖得足够深，我们就可以发现另一颗行星忒伊亚的遗迹。”

The increased density of the masses is believed to come from their high level of iron. Moon rocks also contain high iron levels. So, the researchers think it would make sense if they came from the same place: Theia.
这些斑块密度的增加被认为是由于他们的高铁含量。月球岩石中的铁含量也很高。因此，研究人员认为，如果它们来自同一个地方：忒伊亚，这就讲得通了。

The moon, which orbits Earth at an average distance of about 385,000 km, has a diameter of about 3,475 km, a bit more than a quarter of our planet's diameter.
月球绕地球运行的平均距离约为38.5万公里，其直径约为3475公里，略大于地球直径的四分之一。

Asimow said that, if the theory is correct, some volcanic rocks that reach Earth's surface might provide pieces of Theia.
阿西莫说，如果这个理论是正确的，一些到达地球表面的火山岩可能会提供忒伊亚的碎片。

"If our model is correct, the blobs should have isotopes - trace elements - that are similar to the lunar mantle rocks, which can be tested in future lunar missions," Yuan said.
钱源说：“如果我们的模型是正确的，这些斑块应该具有与月球地幔相似的同位素——微量元素，这可以在未来的月球任务中进行测试。”

Gaining a greater understanding of the hypothesized giant impact could provide information concerning the evolution of Earth and other rocky planets in our solar system and beyond it.
对假设的巨大撞击获得更多的了解，可以提供有关地球和太阳系内外其它岩态行星演化的信息。

"Earth is still the only confirmed habitable planet, and we do not know why," Yuan said. He added the crash set the early conditions for Earth's development and said: "studying its consequences may help us to figure out why Earth is different than other rocky planets."
钱源说：“地球仍然是唯一一颗被确认适合居住的行星，我们不知道为什么。”他补充说这次撞击为地球的发展创造了早期条件，并表示：“研究其后果可能有助于我们弄清楚为什么地球与其他岩石行星有所不同。”