Scientists have recognized since the 1970s that there are two large, mysterious blobs in the deepest part of Earth's mantle.
自 20 世纪 70 年代以来，科学家们已经认识到，在地幔最深处有两个巨大的神秘斑点。
One of the masses is under Africa and the other under the South Pacific Ocean.
其中一处位于非洲下方，另一处位于南太平洋下方。
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质量可能来自地球历史早期的一次巨大碰撞。
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，地球与火星大小的忒伊亚天体之间的碰撞可能创造了月球。
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，忒伊亚的碎片可能仍留在地球内部，沉入地球由铁和镍组成的炽热核心上方的区域。
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来研究他们对该事件的理论。根据这些模拟，他们提出，忒伊亚的大部分被地球吸收，形成了两个质量块，而其余的碎片则形成了月球。
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.
“这些斑点的底部距离我们脚下 2,900 公里。这两个斑点约占地球质量的 2%。地震学检测到它们是因为地震波在这两个区域内的传播速度比周围的地幔慢。每个斑点都是地球质量的两倍。整个月球的质量。所以，这些斑点是巨大的，”袁说。
If the theory is correct, these two masses would represent evidence of the possible moon-forming crash.
如果这个理论是正确的，这两个质量将代表可能的月球形成碰撞的证据。
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."
加州理工学院教授兼研究报告合著者保罗·阿西莫表示，“对于我们是否不仅能在月球上，而且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”，目前尚未达成一致。
The two masses, Asimow added, are the biggest difference "in Earth structure from a simple layered planet."
阿西莫补充说，这两个质量是“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."
该研究的共同作者、中国科学院上海天文台的邓红平说：“这令人难以置信，因为如果我们在地幔中挖掘得足够深，我们就能发现另一颗行星——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.
据信，群众密度的增加是由于其铁含量高。月球岩石中的铁含量也很高。因此，研究人员认为，如果他们来自同一个地方：忒伊亚，那就有意义了。
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 385,000 公里，直径约为 3,475 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.
袁说：“如果我们的模型正确，这些斑点应该含有与月幔岩石类似的同位素（微量元素），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.
更好地了解假设的巨大撞击可以提供有关地球和太阳系内外其他岩石行星演化的信息。
"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."
“地球仍然是唯一被确认的宜居行星，我们不知道为什么，”袁说。他补充说，这次撞击为地球的发展奠定了早期条件，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不同。”
