https://news.asu.edu/20231101-asu-researchers-discover-earths-blobs-are-remnants-ancient-planetary-collision Skip to Main Page Content ASU News Arizona State University ASU News * Home * Explore + Discoveries + Solutions + Creativity + Entrepreneurship + Global Engagement + Arizona Impact + Sun Devil Life + University News + ASU Insight Videos + Athletics + Events + Media Relations + Manage Subscriptions + Follow ASU News + + + * Expert Q&A * Video series + Got a Minute? + Devils in the Details * Magazine + ASU Thrive * Books and essays + Sun Devil Shelf Life + Narrative Storytelling ASU researchers discover Earth's blobs are remnants of an ancient planetary collision --------------------------------------------------------------------- November 1, 2023 In the 1980s, geophysicists made a startling discovery: Two continent-sized blobs of unusual material were found deep near the center of the Earth, one beneath the African continent and one beneath the Pacific Ocean. Each blob is twice the size of the moon, and research over the last decade has shown that they are likely composed of different proportions of elements than the mantle surrounding it. [img_5648] An artistic illustration about Theia impacting the proto-Earth. Artwork by Hernan Canellas/image courtesy of ASU Download Full Image Where did these strange blobs -- formally known as large low-velocity provinces (LLVPs) -- come from? A new study suggests that they are remnants of an ancient planet that violently collided with Earth billions of years ago, in the same giant impact that created our moon. An interdisciplinary team including Arizona State University School of Earth and Space Exploration scientists, was led by ASU alumnus Qian Yuan, currently an O.K. Earl Postdoctoral Fellow at Caltech.The study, published in the journal Nature on Nov. 1, also proposes a solution for another planetary science mystery. For more than 20 years, scientists have known that Earth has giant blobs in its interior, with unusual composition and an unknown origin. These structures are so massive that if you put them on Earth's surface, they would make a layer roughly 60 miles (100 km) thick around the entire planet. Furthermore, it has been hypothesized that the moon was created in the aftermath of a giant impact between Earth and a smaller planet dubbed Theia. Still, no trace of Theia has ever been discovered in the asteroid belt or meteorites. This new study suggests that most of Theia was absorbed into the young Earth, forming the LLVP blobs, while residual debris from the impact coalesced into the moon. "The moon appears to have materials within it representative of both the pre-impact Earth and Theia, but it was thought that any remnants of Theia in the Earth would have been 'erased' and homogenized by billions of years of dynamics (e.g., mantle convection) within the Earth," said Steven Desch, professor at ASU's School of Earth and Space Exploration. "This is the first study to make the case that distinct 'pieces' of Theia still reside within the Earth, at its core-mantle boundary." Scientists first discovered the LLVPs by measuring seismic waves traveling through the Earth. Seismic waves travel at different speeds through different materials, and in the 1980s, the first hints emerged of large-scale three-dimensional variations deep within the structure of the Earth. In the deepest mantle, the seismic wave pattern is dominated by the signatures of two continent-sized structures near the Earth's core. They are interpreted as regions with unusually high iron content, whose increased density and temperature slow down seismic waves passing through, leading to the name "large low-velocity provinces." "But now we have an explanation for them. It appears that Earth's blobs are remnants of a planetary collision that formed our moon," said Ed Garnero, professor at ASU's School of Earth and Space Exploration. "In other words, the massive blobs currently inside Earth, deep beneath our feet, are extraterrestrial. Earth not only has 'blobs,' Earth has extraterrestrial blobs!" [2_18] An artistic illustration shows Theia impacting the proto-Earth. Artwork by Hernan Canellas/image courtesy of ASU [3_14] Parts of the Theia materials sink to and accumulate at the bottom of Earth's mantle, forming the large low-velocity provinces (LLVP) blobs. Artwork by Hernan Canellas/image courtesy of ASU [2_18] [3_14] Yuan, a geophysicist by training, was one day attending a seminar about planet formation given by Mikhail Zolotov, a professor at ASU. Zolotov presented the giant-impact hypothesis, while Qian noted that the moon is relatively rich in iron. Zolotov added that no trace had been found of the impactor that must have collided with the Earth. "Right after Mikhail had said that no one knows where the impactor is now, I had a 'eureka moment' and realized that the iron-rich impactor could have transformed into mantle blobs," Yuan said.. The multidisciplinary team of collaborators modeled different scenarios for Theia's chemical composition and its impact with Earth. The simulations confirmed that the physics of the collision could have led to both the LLVPs' formation and the moon's formation. "This work showed that the large blobs (the LLVPs) in Earth's deep mantle may be made of materials from a planetary body that impacted the proto-Earth and formed the moon," said Mingming Li, professor at ASU's School of Earth and Space Exploration. "Therefore, the moon and the blobs have the same origin." Given such a violent impact, why did Theia's material clump into the two distinct blobs instead of mixing together with the rest of the forming planet? The researchers' simulations showed that much of the energy delivered by Theia's impact remained in the upper half of the mantle, leaving the lower mantle of the Earth cooler than estimated by earlier, lower-resolution impact models. Because the impact did not totally melt the lower mantle, the blobs of iron-rich material from Theia stayed largely intact. "Through mantle convection simulations, we found that the dense, iron-rich materials from Theia could sink to and accumulate at the base of Earth's mantle. These materials could stay there throughout Earth's history of about 4.5 billion years," Li said. "By looking inward, towards Earth's interior, instead of outward, towards the moon, we have found yet another piece of evidence of the cosmic catastrophe that is the moon-forming giant impact," said co-author Travis Gabriel, of the U.S. Geological Survey. "The study really places Earth into the context of the inner solar system formation," said co-author Hongping Deng of the Chinese Academy of Sciences. "Imagine that if we managed to recover some Theia signals from the deepest mantle, we could better understand the architecture and composition of the infant solar system without turning to present-day meteorites with messed-up signals." Additional authors on this study include ASU alumni Byeongkwan Ko, a postdoc at Michigan State University; Paul Asimow and Yoshinori Miyazaki at Caltech; Jacob Kegerreis of NASA Ames Research Center; and Vincent Eke of Durham University. This work was supported by the National Science Foundation, the O.K. Earl Postdoctoral Fellowship at Caltech, the U.S. Geological Survey, NASA and the Caltech Center for Comparative Planetary Evolution. This press release was written by Caltech with contributions from Kim Baptista from ASU's School of Earth and Space Exploration. Discoveries Tempe campus School of Earth and Space Exploration The College of Liberal Arts and Sciences Science Space exploration Research Faculty Degreed alum Alumni Kim Baptista Media Relations and Marketing Manager, School of Earth and Space Exploration 480-727-4662 Kim.Baptista@asu.edu Next Story ASU Law lecture explores law, Latino communities through music A man in a grey suit smiles for the camera. Puerto Rican rapper and singer Bad Bunny might not be the first name that comes to mind when you think about complex legal issues, but he's top-of-mind for at least one law professor.David Lopez, former co-dean of Rutgers Law, delivered a lecture titled "The Law and the Liminality of Latine Communities in 5 Songs" to ASU students, faculty and community members on Oct. 18 at the Beus Center f... Read the article More from Discoveries Advances in X-ray crystallography unveil nature's tiniest secrets Tempe campus , Biodesign Institute , Biodesign Center for Applied Structural Discovery , School of Molecular Sciences --------------------------------------------------------------------- Surf's up: Catch an atmospheric wave as ASU research team launches Gravity Wave Zoo Tempe campus , School of Earth and Space Exploration , The College of Liberal Arts and Sciences , Science --------------------------------------------------------------------- ASU teaching professor brings Dia de los Muertos to life through research, ritual Downtown Phoenix campus , Barrett, The Honors College , Research , Latino / Chicano ASU Law lecture explores law, Latino communities through music --------------------------------------------------------------------- November 1, 2023 Puerto Rican rapper and singer Bad Bunny might not be the first name that comes to mind when you think about complex legal issues, but he's top-of-mind for at least one law professor. David Lopez, former co-dean of Rutgers Law, delivered a lecture titled "The Law and the Liminality of LatineA gender neutral term for Latino. Communities in 5 Songs" to ASU students, faculty and community members on Oct. 18 at the Beus Center for Law and Society. The lecture explored legal decisions and issues that have impacted a sense of belonging for Latino communities across history through music. A man in a grey suit smiles for the camera. David Lopez, visiting distinguished professor, is the former co-dean of Rutgers Law and served two terms as general counsel for the Equal Employment Opportunity Commission. He delivered his lecture "The Law and the Liminality of Latine Communities in 5 Songs" to ASU students, faculty and community members on Oct. 18 at the Beus Center for Law and Society. Download Full Image Lopez is the Sandra Day O'Connor School of Law's inaugural visiting distinguished professor, and has served two terms as general counsel for the Equal Employment Opportunity Commission. And because he is an ASU alum, the visiting professorship serves as a homecoming for the Phoenix native. Willard H. Pedrick Dean and Regents and Foundation Professor of Law Stacy Leeds introduced Lopez to the crowd, calling his time here an "extra treat" for law students. "He is a brilliant legal mind and a connoisseur of the arts, culture and a music man," she said. Lopez began his hour-long lecture with memories of his time as an ASU student, particularly the impact of the community he formed with other Latino students. They would meet in between classes in front of Hayden Library at the Tempe campus to bond and commiserate over their similar struggles. "It was a horizontal space of love where we could be ourselves," he said of the gathering spot, which was a brief respite from the liminalities they faced. Liminality, as defined by Lopez, speaks to an in-between status. "Laws constructed liminal statuses that intersect for a large portion of Latine communities," he said. "They often live in a constant state of displacement." Lopez went on to describe several of those liminalities through five songs, including "El Apagon" by Bad Bunny. "El Apagon" describes the blackouts suffered by Puerto Rico in the aftermath of Hurricane Maria in 2017 and the ongoing displacement of Puerto Ricans due to tax policies. The issues discussed in the song are summed up in the 1901 case Downes v. Bidwell, which addressed whether the Foraker Act violated the U.S. Constitution since Puerto Rico is part of the U.S. The act instituted a civilian government in the territory. The Supreme Court ultimately decided the Constitution did not follow the flag, arguing that Puerto Rico is "foreign in a domestic sense." Another song Lopez cited was "Clandestino" by Lila Downs, which refers to Mexicans crossing the border into the U.S. to go to work -- a widespread practice that continues today. The Bracero farm labor program was in place from 1942 to 1964, leaving many with rich lives on both sides of the border. But the practice also makes the group more exploitable, Lopez said. He cited the case National Labor Relations Board v. Hoffman Plastics of 1982, in which an undocumented man whom the plastics company hired tried to organize in the face of unfair treatment and was fired. The board awards backpay to those who were wrongly fired, but Hoffman Plastics said they didn't have to since the man wasn't a citizen. The Supreme Court did not award him the backpay. In summing up his lecture, Lopez acknowledged the rarity of exploring the law through a cultural lens but argued that music is just as effective in conveying essential messages as anything else, if not more so. "Music reflects and makes an argument and is an argument itself," he said. "It's also resistance against unjust structures." Global Engagement Downtown Phoenix campus Sandra Day O'Connor College of Law Law Music Latino / Chicano Graduate student Lindsay Walker Lindsay Walker Communications Manager, Sandra Day O'Connor College of Law Lindsay.A.Walker@asu.edu Trending on ASU News Woman wearing ASU graduation regallia and smiling at a family member. 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