[新聞] 第一次大型衝擊天體熔融地點已被探明

備註請放最後面 違者新聞文章刪除 1.媒體來源: CNN 2.記者署名: By Jackie Wattles, CNN 3.完整新聞標題: Scientists say they’ve finally found remnants of Theia, an ancient planet that collided with Earth to form the moon 科學家表示，他們終於找到了忒伊亞的遺跡，這是一顆與地球相撞形成月球的古老行星 4.完整新聞內文: Scientists say they’ve finally found remnants of Theia, an ancient planet that collided with Earth to form the moon By Jackie Wattles, CNN 5 minute read Updated 8:37 PM EDT, Fri November 3, 2023 CNN Scientists widely agree that an ancient planet likely smashed into Earth as it was forming billions of years ago, spewing debris that coalesced into the moon that decorates our night sky today. The theory, called the giant-impact hypothesis, explains many fundamental features of the moon and Earth. CNN 科學家普遍認為，一顆古老的行星可能在數十億年前形成時撞上了地球，噴出的碎片合併 成月球，裝飾著我們今天的夜空 。 該理論被稱為大撞擊假說，解釋了月球和地球的許多基本特徵。 But one glaring mystery at the center of this hypothesis has endured: What ever happened to Theia? Direct evidence of its existence has remained elusive. No leftover fragments from the planet have been found in the solar system. And many scientists assumed any debris Theia left behind on Earth was blended in the fiery cauldron of our planet’s interior. A new theory, however, suggests that remnants of the ancient planet remain partially intact, buried beneath our feet. 但這假設的核心有一個明顯的謎團一直存在：忒伊亞到底發生了什麼事？它存在的直接證 據仍然難以捉摸。在太陽系中尚未發現該行星的剩餘碎片。許多科學家認為忒伊亞在地球 上留下的任何碎片都混合在我們星球內部的熾熱大鍋中。 然而，一種新理論表明，這顆古老星球的遺跡仍然部分完好無損，埋在我們腳下。 Molten slabs of Theia could have embedded themselves within Earth’s mantle after impact before solidifying, leaving portions of the ancient planet’s material resting above Earth’s core some 1,800 miles (about 2,900 kilometers) below the surface, according to a study published Wednesday in the journal Nature. A bold new idea If the theory is correct, it would not only provide additional details to fill out the giant-impact hypothesis but also answer a lingering question for geophysicists. 根據週三發表在《自然》雜誌 上的一項研究，忒伊亞的熔融板塊可能在撞擊後凝固之前 嵌入地函中，從而使這顆古老行星的部分物質留在地心上方約1,800 英里（約2,900公里 ）的地表以下。 大膽的新想法 如果理論是正確的，它不僅可以提供更多細節來填補巨大撞擊假說，還可以回答地球物理 學家一個揮之不去的問題。 They were already aware that there are two massive, distinct blobs that are embedded deep within the Earth. The masses — called large low-velocity provinces, or LLVPs — were first detected in the 1980s. One lies beneath Africa and another below the Pacific Ocean. 他們已經意識到地球深處有兩個巨大的、不同的斑點。這些質量塊—稱為大型低剪力波速 群（LLSVP）的構造—首次在 20 世紀 80 年代被發現。一個位於非洲下方，另一個位於 太平洋下方。 These blobs are thousands of kilometers wide and likely more dense with iron compared with the surrounding mantle, making them stand out when measured by seismic waves. But the origins of the blobs — each of which are larger than the moon — remain a mystery to scientists. But for Dr. Qian Yuan, a geophysicist and postdoctoral fellow at the California Institute of Technology and the new study’s lead author, his understanding of LLVPs forever changed when he attended a 2019 seminar at Arizona State University, his alma mater, that outlined the giant-impact hypothesis. 這些斑點有數千公里寬，與周圍的地函相比，鐵的密度可能更高，這 使得它們在地震波 測量時顯得格外突出。但這些斑點的起源—每個斑點都比月球還大—對科學家來說仍然是 個謎。 但對於加州理工學院地球物理學家、博士後研究員、這項新研究的主要作者錢源博士來說 ，當他參加了2019 年在母校亞利桑那州立大學舉行的研討會時，他對LLVP 的理解永遠改 變了，該研討會概述了這個巨大的現象 。 That’s when he learned new details about Theia, the mysterious projectile that presumably struck Earth billions of years ago. And, as a trained geophysicist, he knew of those mysterious blobs hidden in Earth’s mantle. Yuan had a eureka moment, he said. Immediately, he began perusing scientific studies, searching to see whether someone else had proposed that LLVPs might be fragments of Theia. But no one had. Initially, Yuan said, he only told his adviser about his theory. “I was afraid of turning to other people because I (was) afraid others would think I’m too crazy,” Yuan said. 就在那時，他了解到了有關忒伊亞（Theia）的新細節，忒伊亞是一顆可能在數十億年前 撞擊地球的神秘彈頭。 而且，作為一名訓練有素的地球物理學家，他知道那些隱藏在地函中的神秘斑點。 源靈機一動，他說。 他立即開始仔細研究科學研究，看看是否有人提出 LLVP 可能是忒伊亞的碎片。但沒有人 這樣做過。 源說，最初他只是告訴他的顧問他的理論。 「我害怕向其他人求助，因為我擔心別人會認為我太瘋狂了，」源說。 Interdisciplinary research Yuan first proposed his idea in a paper he submitted in 2021. It was rejected three times. Peer reviewers said it lacked sufficient modeling from the giant impact. Then he came across scientists who did just the type of research Yuan needed. Their work, which assigned a certain size to Theia and speed of impact in the modeling, suggested that the ancient planet’s collision likely did not entirely melt Earth’s mantle, allowing the remnants of Theia to cool and form solid structures instead of blending together in Earth’s inner stew. 跨學科研究 源在2021年提交的一篇論文中首次提出了他的想法，但被拒絕了3次。同行評審員表示 ，它缺乏針對巨大影響的足夠模型。 然後他遇到了一些科學家，他們所做的研究正是源所需要的類型。 他們的工作在建模中為忒伊亞指定了一定的大小和撞擊速度，表明這顆古老行星的碰撞可 能沒有完全融化地幔，從而使忒伊亞的殘餘物冷卻並形成固體結構，而不是在地球內部混 合在一起。 This rendering shows Theia colliding with the early Earth. The combination of high-resolution giant impact and mantle convection simulations, mineral physics calculations, and seismic imaging suggests that the lower half of Earth’s mantle remained mostly solid after this impact, and that parts of Theia’s iron-rich mantle sank and accumulated atop Earth's core nearly 4.5 billion years ago, surviving there throughout Earth’s history. 此渲染圖顯示忒伊亞與早期地球相撞。高分辨率巨大撞擊和地函對流模擬、礦物物理計算 和地震成像相結合表明，這次撞擊後，地函的下半部大部分保持固態，而忒伊亞富含鐵的 地函部分下沉並堆積在地核頂部大約 45 億年前，在地球的整個歷史中一直在那裡生存。 “Earth’s mantle is rocky, but it isn’t like solid rock,” said Dr. Steve Desch, a study coauthor and professor of astrophysics at Arizona State’s School of Earth and Space Exploration. “It’s this high-pressure magma that’ s kind of gooey and has the viscosity of peanut butter, and it’s basically sitting on a very hot stove.” In that environment, if the material that makes up the LLVPs was too dense, it wouldn’t be able to pile up in the jagged formations that it appears in, Desch said. And if it were low enough in density, it would simply mix in with the churning mantle. The question was this: What would be the density of the material left behind by Theia? And could it match up with the density of the LLVPs? (Desch had authored his own paper in 2019 that sought to describe the density of the material that Theia would have left behind.) 「地函是岩石，但它不像堅硬的岩石，」該研究的合著者、亞利桑那州立大學地球與太空 探索學院的天文物理學教授史蒂夫·德施博士說。“這種高壓岩漿有點粘，具有花生醬的 粘度，而且它基本上位於一個非常熱的爐子上。” 德施說，在那種環境下，如果構成 LLVPs 的材料太稠密，它就無法堆積在鋸齒狀的地層中 。如果它的密度夠低，它就會簡單地與翻動的地函混合在一起。 問題是：忒伊亞留下的物質的密度是多少？它能與 LLVPs 的密度相符嗎？ （德施在 2019 年撰寫了自己的論文，試圖描述忒伊亞留下的物質的密度。） The researchers sought higher-definition modeling with 100 to 1,000 times more resolution than their previous attempts, Yuan said. And still, the calculations lined up: If Theia were a certain size and consistency, and struck the Earth at a specific speed, the models showed it could, in fact, leave behind massive hunks of its guts within Earth’s mantle and also spawn the debris that would go on to create our moon. “That was very, very, so very exciting,” Yuan said. “That (modeling) hadn’ t been done before.” 源說：研究人員尋求更高分辨率的建模，其分辨率比之前的嘗試高出 100 到 1,000 倍。 儘管如此，計算還是一致的：如果忒伊亞有一定的大小和一致性，並以特定的速度撞擊地 球，模型表明它實際上可以在地函中留下大量的內核，並產生碎片這將繼續創造我們的月 球。 「這非常、非常、非常令人興奮，」源說。“以前沒有做過（建模）。” Building a theory The study Yuan published this week includes coauthors from a variety of disciplines across a range of institutions, including Arizona State, Caltech, the Shanghai Astronomical Observatory and NASA’s Ames Research Center. When asked whether he expects to encounter pushback or controversy over such a novel concept — that slabs of material from an ancient extraterrestrial planet are hidden deep within the Earth — Yuan replied: “I also want to stress this is an idea; this is a hypothesis. 建立理論 源本週發表的研究報告包括來自多個機構的不同學科的合著者，包括亞利桑那州立大學、 加州理工學院、上海天文台和美國宇航局艾姆斯研究中心。 當被問及他是否預計會遇到這樣一個新穎的概念—來自古代外星行星的物質板隱藏在地球 深處—的阻力或爭議時，源回答說：「我還想強調，這是一個想法；這只是一個想法 。” 這是一個假設。 “There’s no way to prove this must be the case,” he added. “I welcome other people to do this (research).” Desch added that, in his view, “this work is compelling. It makes a very strong case.” It even seems “sort of obvious in hindsight.” Dr. Seth Jacobson, an assistant professor of planetary science at Michigan State University, acknowledged that the theory may not, however, soon reach broad acceptance. “沒有辦法證明情況一定如此，”他補充道。“我歡迎其他人來做這件事（研究）。” 德施補充說，在他看來，「這項工作非常引人注目。這是一個非常有力的案例。” 甚至 「事後看來，這似乎是顯而易見的」。 密西根州立大學行星科學助理教授塞斯·雅各布森博士承認，然而，這一理論可能不會很 快被廣泛接受。 “These (LLVPs) — they’re an area themselves of very active research,” said Jacobson, who was not involved in the study. And the tools used to study them are constantly evolving. The idea that Theia created the LLVPs is no doubt an exciting and eye-catching hypothesis, he added, but it’s not the only one out there. 「這些（LLVPs）—它們本身就是一個非常活躍的研究領域，」雅各布森說，他沒有參與 這項研究。用於研究它們的工具也在不斷發展。 他補充說，忒伊亞創造LLVPs的想法無疑是一個令人興奮且引人注目的假設，但這並不是 唯一的假設。 One other theory, for example, posits that LLVPs are actually heaps of oceanic crust that have sunk to the depths of the mantle over billions of years. “I doubt the advocates for other hypotheses (about LLVP formation) are going to abandon them just because this one has appeared,” Jacobson added. “I think we’ll be debating this for quite some time.” 例如，另一種理論認為，LLVPs 實際上是數十億年來沉入地函深處的海洋地殼堆。 「我懷疑其他假設（關於LLVPs形成）的倡導者會僅僅因為這個假設的出現而放棄它們， 」雅各布森補充道。“我想我們會就這個問題爭論相當長一段時間。” 5.完整新聞連結 (或短網址)不可用YAHOO、LINE、MSN等轉載媒體: https://reurl.cc/a48vqZ 6.備註: 黑白雙月正確墜落地點不在南極跟日本，而是在非洲跟太平洋！ https://www.youtube.com/watch?v=lWGRc7l81RY 我也可以一起去鑽探看看嗎？ https://imgur.com/UsJe51O https://imgur.com/UoR8Smy https://imgur.com/dNDXjot https://imgur.com/uphMYun https://imgur.com/mDgpRhT -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 1.34.17.2 (臺灣) ※ 文章網址: https://www.ptt.cc/bbs/Gossiping/M.1699080154.A.9E3.html