{"id":639592,"date":"2026-08-16T03:34:11","date_gmt":"2026-08-16T03:34:11","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/639592\/"},"modified":"2026-08-16T03:34:11","modified_gmt":"2026-08-16T03:34:11","slug":"scientists-discover-remnants-of-theia-the-planet-that-collided-with-earth-4-5-billion-years-ago","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/639592\/","title":{"rendered":"Scientists discover remnants of Theia, the planet that collided with Earth 4.5 billion years ago"},"content":{"rendered":"<ul class=\"MuiTypography-root MuiTypography-paragraph list css-q3r3pl\" data-og-block-area=\"article-blocks\" data-og-block-nth=\"1\" data-og-block-type=\"core\/list\" data-rawhtml=\"1\">\n<li class=\"MuiTypography-root MuiTypography-body1 css-1pbbt52\">Two continent-sized structures deep inside Earth may contain remnants of Theia, the ancient planet thought to have collided with Earth and helped form the Moon.<\/li>\n<li class=\"MuiTypography-root MuiTypography-body1 css-1pbbt52\">Computer simulations suggest dense, iron-rich material from <a href=\"https:\/\/www.thebrighterside.news\/post\/ancient-impact-with-theia-may-have-brought-water-and-life-to-earth\/\" rel=\"nofollow noopener\" target=\"_blank\">Theia<\/a> could have survived the impact, sunk toward Earth\u2019s core and remained there for 4.5 billion years.<\/li>\n<li class=\"MuiTypography-root MuiTypography-body1 css-1pbbt52\">Chemical tests of volcanic rocks and lunar material could help determine whether these deep structures really preserve pieces of a lost planet.<\/li>\n<\/ul>\n<p>Deep beneath Africa and the Pacific Ocean sit two continent-sized masses unlike the mantle around them. Seismic waves slow as they cross these dense regions, and a new explanation traces their origin to the collision that formed the Moon.<\/p>\n<p>The structures, known as large low-velocity provinces, or LLVPs, lie near Earth\u2019s core-mantle boundary. Each is about twice the size of the Moon. Their unusual density and seismic behavior have made their origin a long-running puzzle.<\/p>\n<p>A <a href=\"https:\/\/www.caltech.edu\/\" target=\"_blank\" rel=\"noreferrer noopener nofollow\">Caltech<\/a>-led study published in <a href=\"https:\/\/www.nature.com\/articles\/s41586-023-06589-1\" target=\"_blank\" rel=\"noreferrer noopener nofollow\">Nature<\/a> proposes that the LLVPs may contain remnants of Theia, the protoplanet thought to have struck the young Earth about 4.5 billion years ago. Debris from that impact formed the Moon, while part of Theia may have survived inside Earth.<\/p>\n<p>That possibility would address two mysteries at once. The giant-impact hypothesis explains several major features of the Earth-Moon system, yet direct evidence of Theia has remained elusive.<\/p>\n<p>Earth&#8217;s LLVPs may be remnants of Theia\u2019s mantle. (CREDIT: Deng Hongping and Hangzhou Sphere Studio) Seismic clues point to an iron-rich interior<\/p>\n<p>Geophysicists first recognized the LLVPs through seismic measurements in the 1980s. Waves from earthquakes travel at different speeds through different materials, allowing scientists to map structures that cannot be observed directly.<\/p>\n<p>Near the base of the mantle, seismic waves reveal two enormous regions where their speed drops. Researchers believe these zones contain more iron than the surrounding <a href=\"https:\/\/www.thebrighterside.news\/post\/water-seeping-into-earths-mantle-3-1-billion-years-ago-fueled-early-volcanic-activity-and-plate-tectonics\/\" rel=\"nofollow noopener\" target=\"_blank\">mantle<\/a>, making them denser and helping explain the slower wave speeds.<\/p>\n<p>Qian Yuan, a geophysicist and O.K. Earl Postdoctoral Scholar Research Associate at Caltech, connected that puzzle to Theia in 2019. During a seminar by Arizona State University professor Mikhail Zolotov, Yuan heard that no one knew where the impactor had gone.<\/p>\n<p>\u201cRight after Mikhail had said that no one knows where the impactor is now, I had a &#8216;eureka moment&#8217; and realized that the iron-rich impactor could have transformed into mantle blobs,\u201d says Yuan.<\/p>\n<p>Yuan and collaborators then combined hydrodynamic impact simulations, thermal evolution modeling and mantle convection simulations to test whether material from Theia could enter Earth\u2019s deep mantle and remain distinct.<\/p>\n<p>A collision that did not melt the whole mantle<\/p>\n<p>The simulations suggest the Moon-forming impact could have left <a href=\"https:\/\/www.thebrighterside.news\/post\/the-hidden-mantle-flow-shaping-yellowstones-supervolcano\/\" rel=\"nofollow noopener\" target=\"_blank\">Earth\u2019s mantle<\/a> strongly layered. The upper region became largely molten, while much of the lower mantle remained solid and comparatively cool.<\/p>\n<p>That distinction mattered. The newer simulations indicate much of the impact energy remained in the upper half of the mantle, reducing mixing below.<\/p>\n<p>A portion of Theia\u2019s mantle material could therefore have entered the lower mantle without being thoroughly blended into Earth. Estimates put that material at roughly 0.01 to 0.026 Earth masses, comparable with estimated LLVP masses of about 0.01 to 0.06 Earth masses.<\/p>\n<p>The team also tested likely compositions for Theia\u2019s mantle. Models using 13, 15 and 17 percent iron oxide by weight produced material about 2 to 3.5 percent denser than bulk silicate Earth throughout the lower mantle.<\/p>\n<p>That extra density would have encouraged the material to sink. A <a href=\"https:\/\/www.thebrighterside.news\/post\/two-hidden-continents-above-earths-core-may-be-relics-of-a-primordial-magma-ocean\/\" rel=\"nofollow noopener\" target=\"_blank\">molten blob<\/a> about 50 kilometers wide could, according to the scaling analysis, solidify in as little as 1,000 years.<\/p>\n<p>The researchers compare the process to colored wax in a lava lamp after the heat is turned off. Because the deep mantle remained relatively cool, dense material from Theia could descend rather than disperse completely.<\/p>\n<p>Ancient material survives billions of years below<\/p>\n<p>Long-term mantle simulations tested whether those dense remnants could persist. In a reference model, Theia mantle material was set 2.5 percent denser than its surroundings and introduced as 50-kilometer spheres in the lower half of the mantle.<\/p>\n<p>The material quickly sank toward the core-mantle boundary. Over 4.5 billion years, mantle convection shaped it into two isolated thermochemical piles that resembled the LLVPs.<\/p>\n<p>Illustration of the location of the two large, dense &#8220;blobs&#8221; of iron-rich material near the Earth&#8217;s core. One is underneath the African continent while the other is across the globe beneath the Pacific Ocean. Each blob is nearly twice the size of the Moon. Earth&#8217;s core is illustrated as a gray sphere. (CREDIT: Edward Garnero) <\/p>\n<p>The modeled piles occupied about 3.4 percent of the mantle. Modern LLVPs occupy roughly 4 percent. Their simulated shear-wave velocities were about 1 to 5 percent lower than the surrounding mantle, matching observed seismic reductions.<\/p>\n<p>Most additional models produced similar long-lived piles. Two cases did not: one used material only 1.25 percent denser than the mantle, while another used smaller 25-kilometer blobs with a 2.5 percent density contrast.<\/p>\n<p>The work does not establish that the LLVPs consist entirely of Theia. Present-day structures could include other material, including ancient subducted <a href=\"https:\/\/www.thebrighterside.news\/post\/quiet-for-100000-years-greeces-methana-volcano-may-be-making-a-comeback\/\" rel=\"nofollow noopener\" target=\"_blank\">oceanic crust<\/a>. The initial size, distribution and degree of mixing of Theia\u2019s mantle also remain poorly constrained.<\/p>\n<p>Chemical traces could test the Theia connection<\/p>\n<p>The hypothesis may help explain unusual chemical signatures in volcanic rocks linked to deep mantle plumes. Some ocean-island basalts preserve noble gases that appear older than the Moon-forming impact.<\/p>\n<p>Theia existed before the Moon. Its mantle could therefore have retained ancient nebular gases before colliding with Earth. The research also notes similarities in <a href=\"https:\/\/www.thebrighterside.news\/post\/change-6-samples-reveal-how-earths-magnetosphere-changed-the-solar-wind-reaching-the-moon\/\" rel=\"nofollow noopener\" target=\"_blank\">noble-gas isotope<\/a> ratios between some ocean-island basalts and lunar mare basalts.<\/p>\n<p>Those links remain testable rather than conclusive. The authors call for more detailed chemical and isotopic comparisons between plume-related material associated with the LLVPs and rocks from the Moon.<\/p>\n<p>If the interpretation holds, Earth\u2019s deepest mantle may preserve material from the planet-building era rather than being fully homogenized by billions of years of convection.<\/p>\n<p>Practical implications of the research<\/p>\n<p>The proposed connection gives scientists a new way to investigate the Moon\u2019s origin, the fate of Theia and the long-term evolution of Earth\u2019s interior.<\/p>\n<p>If LLVPs contain ancient Theia material, their survival would show that giant impacts did not necessarily erase large chemical differences inside <a href=\"https:\/\/www.thebrighterside.news\/post\/in-a-dusty-young-solar-system-two-giant-planets-are-taking-shape\/\" rel=\"nofollow noopener\" target=\"_blank\">young planets<\/a>. That could change how researchers reconstruct Earth\u2019s earliest mantle.<\/p>\n<p>It could also guide work on the beginnings of plate tectonics and continent formation. Paul Asimow of Caltech said the next step is to examine whether such ancient deep structures affected \u201cthe onset of subduction before conditions were suitable for modern-style plate tectonics, the formation of the first continents, and the origin of the very oldest surviving terrestrial minerals.\u201d<\/p>\n<p>The idea may extend beyond Earth. Because giant collisions were common during the late stages of planet formation, other rocky worlds could also preserve deep material inherited from ancient impactors.<\/p>\n<p>Schematic diagram illustrating the giant-impact origin of the LLVPs. (CREDIT: Nature) Dig deeper into Earth\u2019s deep mantle and the Moon-forming impact<\/p>\n<p>These resources explore the composition and origins of Earth\u2019s deepest mantle structures, competing explanations for LLVPs, and evidence that helps constrain the ancient collision associated with the Moon\u2019s formation.<\/p>\n<p>Research findings are available online in the journal <a href=\"https:\/\/www.nature.com\/articles\/s41586-023-06589-1\" target=\"_blank\" rel=\"noreferrer noopener nofollow\">Nature<\/a>.<\/p>\n<p>Related Stories<\/p>\n","protected":false},"excerpt":{"rendered":"Two continent-sized structures deep inside Earth may contain remnants of Theia, the ancient planet thought to have collided&hellip;\n","protected":false},"author":2,"featured_media":639593,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[270],"tags":[1282,107814,270562,270563,18,3024,270564,19,17,270565,270566,270567,270568,74600,81517,27388,8197,270569,172,133,74458,451,54118,69668],"class_list":["post-639592","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-caltech","tag-core-mantle-boundary","tag-earth-interior","tag-earth-mantle","tag-eire","tag-geophysics","tag-giant-impact-hypothesis","tag-ie","tag-ireland","tag-large-low-velocity-provinces","tag-llvps","tag-lunar-origin","tag-mantle-convection","tag-moon-formation","tag-new-discoveries","tag-planetary-formation","tag-planetary-science","tag-qian-yuan","tag-research","tag-science","tag-seismic-waves","tag-space","tag-space-news","tag-theia"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/117103090933170119","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/639592","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=639592"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/639592\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/639593"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=639592"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=639592"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=639592"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}