More than two decades have passed since geologists first identified an unusual circular structure buried beneath the North Sea, and now scientists say new evidence could finally solve the mystery.

New research has confirmed that the feature, known as the Silverpit Crater, was likely formed by an asteroid impact as much as 46 million years ago. The discovery ends years of speculation about the mysterious feature’s origins, much of which debated whether the circular structure had been caused by volcanic activity or shifting underground salt deposits.

The research was led by researchers at Heriot-Watt University in Edinburgh and published in Nature Communications.

Combining high-resolution seismic imaging, microscopic analysis of rock samples, and computer simulations, the team behind the new study says their assessment offers the strongest evidence yet that Silverpit represents one of Earth’s relatively rare ancient impact features that have survived throughout time.

The Silverpit Enigma

The three-kilometer feature, which lies approximately 700 meters (2,300 feet) beneath the floor of the southern North Sea, and close to 80 miles off the Yorkshire coast, has long perplexed geologists. Several larger concentric ringlike structures encircle the primary feature, comprising about 12 miles, and since its discovery in 2002, geologists have remained divided over what might have caused it.

Some argued that the weird feature possesses the unmistakable hallmarks of a hypervelocity impact; others maintained that more conventional geological explanations could better account for the circular structure.

Now, after nearly a quarter of a century of debate, the new research appears to finally put the debate over this North Sea enigma to rest.

New Data Sheds Light on the Mystery

“New seismic imaging has given us an unprecedented look at the crater,” said lead author Dr. Uisdean Nicholson, a seismologist with Heriot-Watt University. Of even greater intrigue, the researchers identified microscopic “shocked” quartz and feldspar crystals recovered from an oil exploration well at the same depth as the crater floor.

“We were exceptionally lucky to find these,” according to Nicholson, who called the team’s work “a real ‘needle-in-a-haystack’ effort.”

“These prove the impact crater hypothesis beyond doubt, because they have a fabric that can only be created by extreme shock pressures,” Nicholson said, making them among the strongest lines of evidence available to researchers for confirming ancient impact sites.

Reconstructing an Ancient Impact

By reconstructing the ancient impact event that shaped the Silverpit feature, the team now believes that an asteroid roughly 160 meters wide struck the North Sea at a low angle after approaching from the west. The resulting collision produced the main crater, while launching massive volumes of stone and seawater to levels of up to 1.5 kilometers—the resulting tsunami would have exceeded 100 meters in height.

This ancient impact is still dwarfed when compared to the likes of Mexico’s Chicxulub Crater, which was created by an asteroid that struck our planet 66 million years ago, now widely believed to be responsible for the extinction of the dinosaurs. While smaller by comparison, the Silverpit impact would still have unleashed enormous destructive energy across the surrounding region.

The team’s work also adds to the accumulation of impact features known to scientists, which are relatively rare, despite thousands of asteroids reaching the surface of our world over the last several billion years. However, over such long periods, other geological processes such as erosion, plate tectonics, and volcanic activity have erased most of the remaining evidence of these collisions.

Presently, there are only around 200 impact craters that are known to exist on land, and another few dozen that have been detected beneath Earth’s oceans.

Altogether, while the mystery of Silverpit has now been solved, the new research does more than merely settle a debate: it allows seismologists a deeper look at how asteroid impacts reshape planetary surfaces.

Such knowledge, while improving scientists’ understanding of Earth’s past, could also help provide potentially crucial data for future planetary defense efforts by helping scientists refine models of future impact hazards.

The team’s recent study, “Multiple lines of evidence for a hypervelocity impact origin for the Silverpit Crater,” appeared in Nature Communications.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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There’s more than one way to measure the age of a star in a cluster. But do different age-assigning methods agree?

Assessing Ages

The ages of stars are critical components for many fields of astronomy, from the study of stars themselves to the planets that orbit them and the galaxies they make up. But measuring stellar ages is tricky. It’s considered relatively “easy” to measure the ages of stars in clusters; assuming all stars in a cluster are born from the same material at the same time, the age of the cluster’s stars can be determined using isochrones — theoretical curves describing the temperatures and luminosities of a group of stars of the same age.

However, most stars do not reside in clusters, and to measure the ages of stars that roam the galaxy solo or in small groups, astronomers must use other methods. One method is asteroseismology, in which researchers measure the changes in a star’s brightness or the motion of its surface due to sound waves bouncing around in its interior. Asteroseismology can reveal critical information about a star’s interior structure, composition, and age, but it’s not yet clear how asteroseismic age estimates compare to well-established isochrone-fitting methods for star clusters.

Measurement Matchup

To investigate how these methods compare, Jamie Tayar (University of Florida) and Meridith Joyce (University of Wyoming) compared the age estimates from asteroseismology and isochrone-fitting methods for seven well-studied open and globular clusters. The team scoured the literature for asteroseismic measurements of red giant stars, which are commonly used to calibrate studies of the Milky Way’s history and evolution, and selected a representative age for each cluster from isochrone-fitting methods from the literature.

While the median ages derived from asteroseismic methods fell close to the cluster age for many of the clusters, the team found an enormous amount of spread in the asteroseismic ages of stars within a single cluster. The spread is far greater than expected from the uncertainty in a given asteroseismic measurement, or from the uncertainty arising from the use of different models.

In addition, two of the seven samples had median ages far from the isochrone-fitting cluster age. For these two clusters, especially the well-constrained open cluster NGC 6819, it’s possible that the asteroseismic ages and cluster age are systematically offset from one another — a possibility that would require a dedicated asteroseismic search with a single observatory and a single analysis pipeline to investigate further.

Ages at Odds

Asteroseismic stellar ages are increasingly used to probe the history of the Milky Way and calibrate other age determination methods — so what does it mean for the asteroseismic results to be so varied and potentially offset from the cluster fitting method?

It may mean that asteroseismic measurements require further investigation and calibration before they can achieve the accuracy necessary for galactic archaeology. Part of this endeavor may involve an investigation of binary processes such as accretion or mergers that could alter the masses of individual stars, affecting their inferred ages. These efforts could potentially unlock hundreds of thousands of stellar age measurements from past, present, and future datasets, aiding studies that explore everything from individual stars and their planets to the histories of entire galaxies.

Citation

“Star-Crossed Clusters: Asteroseismic Ages for Individual Stars Are in Tension with the Ages of Their Host Clusters,” Jamie Tayar and Meridith Joyce 2025 ApJL 984 L56. doi:10.3847/2041-8213/adcd6f

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