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Scientists Detect Shape-Shifting Along Earth’s Solid Inner Core

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Scientists Detect Shape-Shifting Along Earth’s Solid Inner Core

The inner core at the center of the Earth, a ball of iron and nickel about 1,500 miles wide, may not be perfectly solid.

A new study finds evidence that the inner core’s outer boundary has noticeably changed shape over the past few decades.

“The most likely thing is the outer core is kind of tugging on the inner core and making it move a little bit,” said John Vidale, a professor of earth sciences at the University of Southern California.

Dr. Vidale and his colleagues reported their findings on Monday in the journal Nature Geoscience.

That adds to the mysteries about the planet’s center. Geophysicists have previously reported that the inner core does not spin at exactly the same rate as the rest of Earth. They also showed that the pace of rotation changes — the inner core appeared to be spinning slightly faster than the outer layers a couple of decades ago, and now it is spinning slightly slower.

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The inner core is the deepest of Earth’s geological layers. The crust — the layer that we live on — is just a few miles thick. Below that, filling up 84 percent of the planet, is the 1,800-mile-thick mantle, which is soft enough in places to flow up and down and generate the forces that push the continents around. Between the mantle and the inner core is the liquid outer core.

Scientists of course cannot cut into Earth and directly observe its insides. Instead, their knowledge is inferred from the vibrations generated by earthquakes that pass through the planet. The speed and the direction of the seismic vibrations change depending on the density and the elasticity of the rocks.

For this study, Dr. Vidale and his colleagues looked at earthquakes in the South Sandwich Islands, a volcanic chain in the South Atlantic Ocean.

So many earthquakes happen there that sometimes a new event is almost identical in magnitude and location to one that occurred years earlier.

The scientists identified more than 100 such “earthquake pairs,” analyzing readings from 1991 to 2004 at two arrays of seismometers more than 8,000 miles away from the islands, one near Fairbanks, Alaska, the other in Yellowknife, Canada.

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The analysis originally aimed to improve on earlier work that suggested a slowing of the inner core’s spin. But the scientists did not understand aspects of the signals at the Yellowknife array.

“Basically, the wiggles are different,” Dr. Vidale said.

By coincidence, for some of the pairs, the inner core was in the same orientation during both quakes.

Identical earthquake vibrations passing through the identical part of the Earth should have produced identical seismic signals at Fairbanks and Yellowknife. At Fairbanks, that was true, but at Yellowknife the signals were different.

Because Yellowknife is somewhat closer to the South Sandwich Islands than Fairbanks is, the seismic waves from the islands’ earthquakes did not travel as deeply into the inner core as those reaching Fairbanks. That suggested something had changed near the outer boundary of the inner core.

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Turbulent flow in the outer core or gravitational pull from denser parts of the mantle could have deformed the inner core boundary, which might account for the change in the seismic signals, Dr. Vidale said.

“We expect it’s soft because it’s near melting point,” he said. “So it’s no surprise if it deforms.”

The new findings will not be the last on the subject. “The offered interpretation is sound,” said Hrvoje Tkalcic, a professor of geophysics at the Australian National University who was not involved with the research, “although it is not the only possible explanation, as the authors acknowledge.”

In recent years, geophysicists have argued over whether differences in the seismic signals are caused by a change in the rotation rate or by a change in the shape of the inner core. “This study thus reconciles the last debate by proposing a combination of both causes,” Dr. Tkalcic said.

Lianxing Wen, a professor of geosciences at Stony Brook University in New York who in 2006 reported possible changes of shape at the inner-core boundary, remains unconvinced that the inner core spins at a rate different from that of the rest of Earth.

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Dr. Wen said the Yellowknife data was inconsistent with that hypothesis. “Ordinarily, such inconsistencies should lead to an abandonment of the original inconsistent interpretation,” he said.

A change in shape, without any change in the rotation rate, was enough to explain the seismic data, Dr. Wen said.

Even Dr. Vidale is not completely convinced he is correct. “We’re pretty sure we were right, but this isn’t a bulletproof paper,” he said. “How sure? I sort of put it at 90 percent.”

Dr. Tkalcic said more data was needed to resolve the question, which “can be achieved by building seismological infrastructure in remote areas of the planet, including the ocean floor.”

Xiaodong Song, a professor at Peking University in China who in the mid-1990s was one of the first to propose that the inner core was spinning at a different speed from that of the Earth’s surface, agreed.

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“This new study,” Dr. Song said, “should motivate a new round of exploration into strange behaviors at the heart of the planet.”

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China Launches Reusable Rocket in Race With SpaceX

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Video released by Chinese state media shows a state-owned aerospace company launching a rocket and recovering part of it on Friday. The successful launch of a reusable rocket was a major step for China toward challenging SpaceX’s satellite internet dominance.

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Nobel Prize winner leaving UC Berkeley for new role in China

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Nobel Prize winner leaving UC Berkeley for new role in China

Nobel Prize recipient Omar Yaghi is leaving his role at UC Berkeley to lead the development of a new artificial intelligence institute at Tsinghua University in Beijing, the Chinese university announced.

Yaghi will head the AI Chemistry and Materials Research Institute at Tsinghua, where he was appointed an honorary professor in 2022. Known as AIMATRY (AI × Materials × Chemistry), the new center will focus on material design and synthesis through artificial intelligence, according to a statement from the university.

In 2025, Yaghi shared the Nobel Prize in chemistry with Susumu Kitagawa of Kyoto University and Richard Robson of the University of Melbourne for their development of metal-organic frameworks, a type of super-porous material in which metal ions and carbon-based molecules combine to form crystals with exceptionally large surface areas.

The material has the potential to combat climate change by capturing and storing carbon or other pollutants, and by extracting water from the atmosphere in water-scarce areas. Upon awarding the prize, a member of the Nobel committee likened the technology’s ability to store enormous amounts of stuff in seemingly compact spaces to Hermione Granger’s enchanted handbag in the Harry Potter series.

Yaghi’s Irvine-based company, Atoco, has said it will start taking orders later this year for its technology that harvests water from the air.

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A representative for Yaghi said he was not yet available to respond to questions.

China is one of several countries that has been actively recruiting scientists from the U.S., where the Trump administration has slashed science funding, suspended research grants, fired science advisors and tightened immigration restrictions.

“For many, many years, our funding was very competitive; if you worked hard and you were doing good research, you would get funding,” Yaghi said of the U.S. in an interview with Scientific American earlier this year. “The current state is not so encouraging because of the cutting back on grants and support of science by the very agencies that many university researchers rely on.”

Yaghi was born in Jordan to Palestinian refugees, and immigrated to the U.S. when he was 15 to study.

“We’ve learned over and over in human civilization that scholars can move across borders,” Yaghi told the New York Times last year. “This is how knowledge spread and how vast regions of the world lifted themselves out of poverty.”

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Trump administration seeks to limit federal funding that doesn’t ‘advance’ presidential policies

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Trump administration seeks to limit federal funding that doesn’t ‘advance’ presidential policies

A new rule proposed by the White House Office of Management and Budget would fundamentally overhaul the way federal grants are awarded and overseen — a sweeping change that one scientific society said “would all but end the use of scientific merit in the selection of grants and programs across the government.”

Proposed in late May, the rule would give political appointees unprecedented control over federal grants for research, education and infrastructure, and specifies that government funds can only be spent on projects “aligned with administration policies and priorities,” according to a copy of the proposed rule.

The rule would also restrict research topics, limit U.S. scientists’ ability to collaborate with colleagues in other countries and make it easier for the government to suspend or cancel grants at any time.

The changes are intended to improve “transparency, accountability, and oversight for Federal awards” while “ensuring that American tax dollars are not wasted or misused,” according to the White House office.

But critics say that if the rule is implemented, the final sign-off for grants will no longer be in the hands of subject-matter experts within individual agencies, but in those of political appointees.

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“This touches all parts of American life,” said Dr. Eric Rafla-Yuan, a psychiatrist who practices at the Veterans Administration and San Diego County’s psychiatric hospital.

“Control of how all of the federal grants and programs are funded will fall under a small group of highly partisan individuals who would have very few limits on how they spend these billions of taxpayer dollars,” said Rafla-Yuan, who also chairs the Committee to Protect Public Mental Health advocacy group. “This touches everyone’s life, even if they don’t realize it.”

OMB published the proposed rule May 29, opening a 45-day comment period that closes July 13.

Opposition to the proposed rule has mobilized multiple sectors of society. Professional groups representing cancer researchers, civil engineers, county governments, medical schools, housing agencies, city and municipal governments, nonprofits and others have publicly expressed concerns about potential consequences.

By midday Thursday, the Federal Register logged nearly 100,000 comments about the proposal, many of them expressing concern.

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“I understand the need for oversight, fiscal responsibility, and accountability. That is not the issue,” wrote Jack Feldman, a neuroscientist who holds the David Geffen School of Medicine Chair in Neuroscience at UCLA. “The issue is whether scientific research is to be judged by scientific merit, or whether it can be approved, denied, or terminated according to broad political criteria that may change from one administration to the next.”

Crucially, the rule converts policies governing federal grants from “guidance” into binding regulations that all agencies would be required to follow. It would give political appointees power to override federal agencies’ merit-based reviews and mandate that a political appointee review decisions to ensure that all awards “demonstrably advance the President’s policy priorities.”

The elevation of political appointees in what were previously merit-based decisions has alarmed many scientists.

“The proposed rule changes would all but end the use of scientific merit in the selection of grants and programs across the government,” read a statement from the Planetary Society, a nonprofit dedicated to space research.

Researchers and science groups have also expressed concern about a section of the rule prohibiting the promotion of “theories of disparate-impact liability” — a legal concept that refers to policies that appear neutral but cause disproportionate harm to certain groups.

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The section’s vague language and many loopholes could have a chilling effect on any research that studies the effects of a disease, policy or public health intervention on any specific group of people, Rafla-Yuan said.

As an example, he said, “if there’s a specific age range that is at higher risk for suicide, and we want to figure out, well, what’s going on with people that are aged 14 to 19 … we can’t do that under the wording in this rule.”

New restrictions on collaborations with scientists in other countries would hinder opportunities for U.S. researchers and limit innovation, said Joanne Padrón Carney, chief government relations officer for the American Assn. for the Advancement of Science.

“Science is a global enterprise. Especially in biomedical and public health fields, diseases don’t care about borders or government policies,” she said.

California’s congressional delegation sent a letter Wednesday asking OMB to rescind the proposal, outlining concerns about its impact on scientific innovation, U.S. competitiveness and the fiscal stability of local governments, many of which rely on federal grants for local services.

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The proposed rule grants the federal government broad powers to suspend or cancel grants for any reason, introducing “unprecedented unpredictability into local governance,” the lawmakers wrote, “leaving vital infrastructure projects unfinished and abandoning vulnerable populations who rely on these services.”

Republican Sen. Susan Collins has also asked the White House to withdraw certain parts of the letter and extend the public comment period, saying the proposed rule as written would “harm small and rural communities, undermine scientific and biomedical research, and conflict with Congress’ control over the federal funding process.”

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