Earth’s largest modern crater discovered in Southern China

The Jinlin crater is 900 meters in diameter and dates to Earth’s current geological epoch.

American Institute of Physics

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A panoramic aerial drone image of the Jinlin crater with the approximate location of the crater rim labeled, with an insert of the crater floor, which shows a mix of granite weathered soil and granite fragments. The yellow ruler is 20 centimeters long.

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Credit: Ming Chen

WASHINGTON, Nov. 12, 2025 – A newly discovered, remarkably well-preserved impact crater is shedding fresh light on how extraterrestrial bodies collide with Earth.

In the journal Matter and Radiation at Extremes, by AIP Publishing, researchers from Shanghai and Guangzhou, China, report the discovery of the Jinlin crater: an impact structure nestled on a hillside and preserved within a thick granite weathering crust.

Located in Zhaoqing, Guangdong Province, China, it is one of only about 200 identified craters worldwide and is very young in geological years. Based on measurements of nearby soil erosion, it likely formed during the early-to-mid Holocene — our current geological epoch, which began at the end of the last ice age about 11,700 years ago. With a diameter of 900 meters, it is the largest known impact crater from this era — far exceeding Russia’s 300-meter Macha crater, previously the largest known Holocene impact structure.

“This discovery shows that the scale of impacts of small extraterrestrial objects on the Earth in the Holocene is far greater than previously recorded,” said author Ming Chen.

In this case, the “small” impactor in question was a meteorite rather than a comet, which would have left a crater at least 10 kilometers wide. However, the research team has not yet determined whether the meteorite was made of iron or stone.

One of the most surprising traits of this crater is how well-preserved it is, especially given the region’s monsoons, heavy rainfall, and high humidity — all conditions that accelerate erosion. Within the granite layers that help to protect and preserve its impact structure, the researchers found many pieces of quartz with unique microfeatures, called planar deformation features, that geologists use as evidence of some type of impacts.

“On the Earth, the formation of planar deformation features in quartz is only from the intense shockwaves generated by celestial body impacts, and its formation pressure ranges from 10 to 35 gigapascals, which is a shock effect that cannot be produced by any geological process of the Earth itself,” said Chen.

It is generally believed that throughout Earth’s history, every point on its surface has faced roughly equal odds of being struck by an extraterrestrial object. However, geological differences mean that the historical footprints of these impacts eroded at varying rates, and some have fully disappeared. This makes the Jinlin Crater’s discovery particularly significant.

“The impact crater is a true record of Earth’s impact history,” said Chen. “The discovery of the Earth impact crater can provide us with a more objective basis for understanding the distribution, geological evolution, and impact history and regulation of small extraterrestrial bodies.”

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The article “Jinlin crater, Guangdong Province, China: Impact origin confirmed” is authored by Ming Chen, Dayong Tan, Wenge Yang, Ho-Kwang Mao, Xiande Xie, Feng Yin, and Jinfu Shu. It was published in Matter and Radiation at Extremes and can be accessed at https://doi.org/10.1063/5.0301625.

ABOUT THE JOURNAL

Matter and Radiation at Extremes (MRE), published by China Academy of Engineering Physics (CAEP), is committed to the publication of original research and comprehensive and in-depth review papers in all areas of experimental and theoretical physics on matter and radiation at extremes. MRE aims to provide a peer-reviewed Open-Access platform for the international physics community and promote worldwide dissemination of the latest and best research in related fields. See https://pubs.aip.org/aip/mre.

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Journal

Matter and Radiation at Extremes

DOI

10.1063/5.0301625 

Article Title

Jinlin crater, Guangdong Province, China: Impact origin confirmed

DECRIMINALIZE DRUGS

New discovery suggests opium use in ancient cultures, from Xerxes to King Tut

Yale University

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New Haven, Conn. — Examination of an ancient alabaster vase in the Yale Peabody Museum’s Babylonian Collection has revealed traces of opiates, providing the clearest evidence to date of broad opium use in ancient Egyptian society, according to a new study by the Yale Ancient Pharmacology Program (YAPP). 

The finding suggests that similar ancient Egyptian alabaster vessels — all made of calcite mined from the same quarries in Egypt — including several exquisite examples discovered in the tomb of Pharaoh Tutankhamun — could also contain traces of ancient opiates, said Andrew J. Koh, YAPP’s principal investigator and the study’s lead author. 

“Our findings combined with prior research indicate that opium use was more than accidental or sporadic in ancient Egyptian cultures and surrounding lands and was, to some degree, a fixture of daily life,” said Koh, a research scientist at the Yale Peabody Museum. “We think it’s possible, if not probable, that alabaster jars found in King Tut’s tomb contained opium as part of an ancient tradition of opiate use that we are only now beginning to understand.”

The study, published in the Journal of Eastern Mediterranean Archaeology, is coauthored by Agnete W. Lassen, associate curator of the Yale Babylonian Collection, and Alison M. Crandall, YAPP’s lab manager. 

The alabaster vase is inscribed in four ancient languages — Akkadian, Elamite, Persian, and Egyptian — to Xerxes I, who ruled the Achaemenid Empire from 486 to 465 BCE. Based in Persia, the empire at its height included Egypt as well as Mesopotamia, the Levant, Anatolia, and parts of Eastern Arabia and Central Asia.  

A second inscription on the vase written in Demotic script — a simplified form of ancient Egyptian writing — indicates that it has a capacity of about 1,200 millimeters. (It is 22 centimeters tall.) Intact examples of inscribed ancient Egyptian alabaster vessels are exceptionally rare, likely numbering less than 10 in collections worldwide, the researchers noted. 

The provenances of the intact vessels are generally unknown, the researchers said, but they at least span the reigns of Achaemenid emperors Darius, Xerxes, and Artaxerxes, a period covering 550 to 425 BCE. Yale’s vase has been part of the Babylonian Collection since shortly after the assemblage of about 40,000 ancient artifacts was established at the university in 1911. 

Based at the Peabody Museum, YAPP harnesses ethnography, science, and technology to better understand how people lived thousands of years ago. Its researchers study the organic residues found on or within ancient vessels, providing insight into ancient people’s diets and lifestyles. The program has developed specific methods for analyzing organic residues — which degrade and decompose over time and are susceptible to contamination — found in artifacts in museum collections or those that have been recently excavated. 

“Scholars tend to study and admire ancient vessels for their aesthetic qualities, but our program focuses on how they were used and the organic substances they contained, knowledge that reveals a great deal of information about the daily lives of ancient peoples, included what they ate, the medicines they used, and how they spent their leisure time,” Koh said.  

For the new study, Koh’s interest was initially piqued after observing dark-brown aromatic residues inside the vase. 

YAPP’s analysis of the residues revealed definitive evidence for noscapine, hydrocotarnine, morphine, thebaine, and papaverine — well-known diagnostic biomarkers for opium. 

Researchers say the results echo the discovery of opiate residues in a group of Egyptian alabaster vessels and Cypriot base-ring juglets found in an ordinary tomb, likely a merchant family, in Sedment, Egypt, located south of Cairo, that dates to the New Kingdom, the Egyptian empire that stretched from the 16th to the 11th century BCE.

The two findings, which stretch over a millennium and across socio-economic groups, raise the distinct possibility that opium is present among the large quantity of alabaster vessels found in Tutankhamun’s tomb in the Valley of the Kings, Koh said. 

There are clear signals of opium usage that goes beyond medicinal usage and into the spiritual realm throughout antiquity, stretching from ancient Mesopotamia to Egypt and through the Aegean, he said. During Tutankhamun's lifetime, for example, people in Crete were associated with the so-called “poppy goddess” in clearly ritualistic contexts. The poppy plant is mentioned in multiple ancient texts including the Ebers Papyrus, Hippocrates, Dioscorides’s De Materia Medica, and Galen. 

Egyptologist and archaeologist Howard Carter’s discovery of Tutankhamun’s tomb in November 1922 yielded an enormous haul of artifacts, including a vast number of exquisitely preserved Egyptian alabaster vessels that likely represented the finest available during Tutankhamen’s reign, which last from 1,333 to 1,323 BCE. 

In 1933, the analytical chemist Alfred Lucas, a member of Carter’s research team, performed a cursory chemical study of the vessels, many of which contained sticky, dark brown, aromatic organics. At the time, Lucas was unable to chemically identify the organic materials, but he determined that most were not unguents or perfumes. 

“That Lucas questioned whether any of the vessels contained perfumes or unguents at all and did not identify the remaining vessel contents as primarily aromatic in nature is significant given that the prevailing conventions at the time would have pressured him to do so,” Koh said.

No further analysis of the organic materials has been conducted since Lucas’ early attempt. The vessels — along with most other artifacts from Tutankhamun’s tomb — are housed at the Grand Egyptian Museum in Giza, Egypt.

After his historic discovery, Carter had noted an ancient looting incident that targeted the contents of the alabaster vessels, the researchers said. Finger marks found inside the vessels suggested that the looters had attempted to meticulously scrape out their contents to the dregs. Many of the looted vessels contained that same dark-brown, aromatic substances that Lucas concluded were not perfumes, the researchers note. A few of the vessels were not looted and remain filled with their original contents. 

Those contents, whatever they were, were considered important enough to accompany Tutankhamen into the afterlife and to inspire grave robbers to risk their lives in an attempted theft, Koh said. 

It is unlikely, he added, that ancient people would have assigned such value to the standard unguents and perfumes of the day. 

“We now have found opiate chemical signatures that Egyptian alabaster vessels attached to elite societies in Mesopotamia and embedded in more ordinary cultural circumstances within ancient Egypt,” Koh said. “It’s possible these vessels were easily recognizable cultural markers for opium use in ancient times, just as hookahs today are attached to shisha tobacco consumption. Analyzing the contents of the jars from King Tut’s tomb would further clarify the role of opium in these ancient societies.”

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DOI

10.5325/jeasmedarcherstu.13.3.0317 

Article Title

The Pharmacopeia of Ancient Egyptian Alabaster Vessels: A Transdisciplinary Approach with Legacy Artifacts

 

Alloys that 'remember' their shape can prevent railroad damage

University of Illinois Grainger College of Engineering

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A concrete tie deforming under the weight of rail traffic. The arrow indicates where SMAs were inserted to demonstrate adaptive reinforcement.

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Credit: The Grainger College of Engineering at the University of Illinois Urbana-Champaign

In railroad tracks, rail ties hold the rails in place and ensure that their separation does not change. Modern concrete ties warp and crack through repeated use, leading to safety concerns including derailment if not regularly maintained.

Research from The Grainger College of Engineering at the University of Illinois Urbana-Champaign shows that damage to concrete ties can be mitigated using shape memory alloys (SMAs), metals with the ability to return to their original shape after they are deformed. In a study led by civil and environmental engineering professor Bassem Andrawes, ties warped by simulated rail traffic were shown to return to their original state with the help of SMAs activated by induction heating. The results were published in the Journal of Transportation Engineering, Part A: Systems

“We’re doing something that I think is unprecedented in rail transportation engineering,” Andrawes said. “We’re working with a commercial supplier of concrete rail ties to implement and test our designs. For our publication, we went beyond laboratory experiments and demonstrated compliance with rail industry standards. We’re very excited to continue our industrial partnership and develop a practical, working design.”

Degradation in concrete is traditionally prevented through the process of prestressing, in which pre-tensioned steel rods are inserted to exert forces which counteract the effects of heavy loads. While this technique is applied in rail ties, the difficulty is that different parts of the tie experience different stresses. In addition, the ties shift as the ballast – the gavel bed distributing weight and providing drainage – settles in response to traffic.

Andrawes believes that SMAs are an ideal solution because they can be inserted into ties then independently controlled with self-contained heat sources. The reinforcement they provide could quickly adapt to the specific circumstances the tie is experiencing at different locations in its structure.

“SMAs are examples of what we call ‘smart materials,’” Andrawes said. “You can deform them, twist them into wild new shapes, but they retain memory of their original state in the molecular structure. When you apply heat, they know to return to that state. So, if you just have a heat source, then the SMA can guide a concrete structure back to the desired shape stored in the alloy’s memory.”

Working with Illinois Grainger Engineering civil and environmental engineering graduate student Ernesto Pérez-Claros, Andrawes decided to use induction heating, in which the heat to restore the SMAs to their original shape is provided by a time-varying electromagnetic field. This was done to ensure that the electrical hardware would not need to be inserted inside the tie.

The research proceeded in three phases. First, the researchers worked with Rocla Concrete Tie, Inc. to cast their design in commercially available concrete rail ties. Second, the researchers conducted laboratory experiments to quantify the impacts of different lengths of SMAs in the ties. Finally, ties were subjected to stress tests simulating rail traffic, and the prototypes exceeded the standards of the American Railway Engineering and Maintenance-of-Way Association (AREMA).

“It was important to us that we actually make something that goes out of the lab and into practice,” Andrawes said. “Showing that our design meets and even exceeds AREMA specifications means that it’s not just academic research. This is something that railroads can use, and we intend to guide it to the point where it can be adopted.”

The researchers plan to continue working with Rocla to commercialize the technology. They also plan to submit their prototypes for full testing with real rail traffic at the Federal Railroad Administration Transportation Technology Center in Pueblo, Colorado.

The study, “Experimental Testing of Concrete Crossties Prestressed with Shape Memory Alloys,” is available online. DOI: 10.1061/JTEPBS.TEENG-8982

Support was provided by the Transportation Research Board and by the Transportation Infrastructure Precast Innovation Center through the University Transportation Center program of the U.S. Department of Transportation.

Illinois Grainger Engineering Affiliations:

Bassem O. Andrawes is a professor of civil and environmental engineering in the Department of Civil and Environmental Engineering. He is the director of the Transportation Infrastructure Precast Innovation Center. He holds a CEE Excellence Fellow appointment.

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Journal

Journal of Transportation Engineering Part A Systems

DOI

10.1061/JTEPBS.TEENG-8982 

Article Title

Experimental Testing of Concrete Crossties Prestressed with Shape Memory Alloys

 

Admitting imposter feelings may undermine professors’ perceived competence, study finds

Sharing an internal sense of inadequacy may shape how students perceive their professors’ overall competence, effectiveness

Colorado State University

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University faculty are expected to have confidence in the classroom. However, the pressures of life in academia can often lead to a sense of self-doubt – commonly known as impostor syndrome – despite objective success. 

New research from Colorado State University demonstrates that faculty sharing an internal sense of unease and inadequacy may significantly shape the ways students perceive their professors’ overall competence, likeability and effectiveness at teaching. 

The results show that students found a hypothetical professor who publicly acknowledged feelings of being an impostor to be less hirable than an equally accomplished faculty member who did not make the same disclosure. The findings have implications for faculty development and retention strategies as well as mentorship activities with students. They could also be valuable beyond academia as leaders working in many capacities aim to demonstrate vulnerability in the name of building trust within their teams. 

The work was led at CSU by Ph.D. candidate Alexa Jayne and published in Scholarship of Teaching and Learning in Psychology. Jayne said she became interested in the topic while working as a teaching assistant in the Department of Psychology. Through interactions with students, she began to recognize her own feelings of impostor syndrome. 

“Teaching was a beautiful experience that I loved, but I also noticed that I was not feeling capable or good enough in spite of the objective success I was having,” Jayne said. “That led me want to explore the phenomenon in more detail, but especially the ways it affects how others externally perceive you, which was a gap in the existing literature.” 

Impostor syndrome or phenomenon refers to a psychological pattern in which individuals have a persistent fear of being exposed as a “fraud,” despite evident success. It is common in higher education, where many high-performing people can struggle with receiving feedback in instances such as paper reviews or when pursuing tenure, for example. 

To study the phenomenon, students in the study were presented two brief and nearly identical vignettes about a hypothetical tenured professor. While the subject was described as well accomplished in both instances, one version also specifically listed their tendency to attribute success to external factors and a fear of being exposed as a fraud despite consistent positive evaluations by peers and students. Students were then asked to evaluate the teacher based on a range of variables. Those variables included measures such as likeability as well as questions about what the estimated average grade in their class would be, what their salary was and whether they as students would enroll in the class. Demographic information about the hypothetical teacher was kept purposefully vague to try and limit areas of potential bias. 

The participants thought the professor who mentioned feelings of self-doubt had significantly less experience and earned $10,000 less than the one described in the control group. However, in both cases the hypothetical teacher was found to be equally likeable. Jayne said that suggests that displaying minor flaws can be humanizing and supports approachability. She said the results of the survey also showed that students were equally likely to want to enroll in both classes.  

The findings illustrate a careful balance instructors and faculty must navigate, Jayne noted.    

“At least in this study, it seems students do still perceive or equate confidence with competence. That doesn’t mean that is the right way to navigate these spaces though,” she said. “Instead, it means these disclosures need to be thoughtfully done so that instructors can find ways to connect with students without unintentionally undermining their own standing.” 

Jayne added that this research could be particularly relevant to groups that are pre-disposed to feelings of impostor syndrome, such as women in STEM, whose experiences inform their mentorship activities throughout their careers. 

“I don’t want this research to be taken as, ‘You should never be vulnerable in a classroom,’” she said. “Rather, I hope this is a step towards normalizing these feelings and supporting the retention and advancement of faculty – especially in those marginalized groups we know can suffer from these feelings – by addressing them in a structured way.” 

Jayne is finishing her Ph.D. under Professor Bryan Dik in the Department of Psychology and plans to graduate in spring 2026.  

Dik’s research at CSU broadly explores meaning and purpose in the workplace. He said this paper addresses the pressures and expectations that can come with work that a person may feel called to do. That makes it applicable beyond just higher education settings. 

“This work relates to what our team describes as the ‘dark side’ of calling – negative outcomes that sometimes result from pursuing meaningful work,” he said. “In the future, we hope to examine the role of different demographic variables and their tangible impacts on hiring, promotions and student engagement – especially for early career faculty or those from marginalized groups that are already vulnerable to bias.”

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Journal

Scholarship of Teaching and Learning in Psychology

DOI

10.1037/stl0000461 

Article Title

Conflating competence with confidence: Student perceptions of a professor with imposter phenomenon.

Article Publication Date

12-Nov-2025