The Sun is experiencing long-term changes, as revealed by an international team of researchers led by the University of Birmingham, who have identified a major squeeze in the four most recent solar activity cycles.

A recent paper in the Monthly Notices of the Royal Astronomical Society by the University of Birmingham-led team reveals that Solar magnetic activity is now being forced into a shallow layer of the Sun, just beneath the solar surface, marking a major change to our host star’s active biorhythm.

The Sun’s 11-year cycles of activity range from a low ebb to robust periods, producing explosive events such as highly charged particle ejections and coronal mass ejections, which are major drivers of dangerous space weather.

Inside the Sun

Below the solar surface, processes generate the Sun’s magnetic field, which drives the solar cycles, which in turn drive space weather. Space weather can be extremely hazardous to the electronic and communications infrastructure we rely on, both in space and on Earth’s surface, including GPS systems and the power grid. Therefore, as our reliance on that infrastructure grows, accurately predicting space weather has become an increasingly important concern.

Scientists have primarily used external markers, such as sunspots, to track solar activity, but, like in any system, much of what drives the Sun occurs beneath the surface. To pierce the solar veil, the researchers have adopted a technique called helioseismology, which allows them to listen to small sound waves from inside the Sun. These waves reveal minute changes beneath the surface, providing a very different understanding of the most recent solar cycles than what could be observed from external markers.

A History of the Sun

The research relied on nearly four decades of helioseismic data collected by the Birmingham Solar Oscillations Network (BiSON) of six telescopes located around the globe. Finally, researchers had sufficient historical data on the Sun’s inner workings to conduct a lengthy study of how these workings have changed over time.

In their analysis of that data, the international team identified a slow but growing change in the structure of the Sun’s interior, occurring across multiple cycles.

“The Sun has its own ‘active biorhythm’ creating rising and falling magnetic activity that shapes space weather,” said lead author Professor Bill Chaplin, from the University of Birmingham. “However, traditional surface measures don’t capture the full story – that the Sun may be entering a different mode of behavior unfolding over decades.”

“We have uncovered evidence of systematic changes in the solar activity cycle,” Chaplin added. “Crucially, magnetic activity is becoming more tightly confined near the surface with each cycle. This is the first such discovery and would have been impossible without the long BiSON observations.”

A Deeper Look

From 1987 through 2025, during cycles 22-25, shifts in p-mode oscillations driven by magnetic activity revealed internal changes in the Sun. The team identified three different groups of oscillations, marked by the low, medium, and high-frequency bands, each penetrating the solar surface to a different depth. Compared with traditional external markers, the data revealed three unique elements. 

Since cycle 23, oscillation frequencies and external markers have begun telling very different stories, indicating major changes in the Sun’s internal workings. As time goes on, more and more of the changes are occurring near the surface, at depths of less than 1,000 kilometers. In the most recent cycle, 25, helioseismic data are giving off much stronger indications of this activity than surface markers.

According to the researchers, weakening magnetic fields cannot account for the changes observed, suggesting a major structural reorganization beneath the Sun’s surface. 

The team says that continuing exploitation of the BiSON data into cycle 26 will be essential to determining whether this indicates a sustained change in solar activity. 

The paper, “Sub-Surface Structural Changes Associated with Successive 11-yr Solar Activity Cycles Have Been Progressively More Confined Near the Surface: New Helioseismic Results on Cycles 22– 25 from BiSON,” appeared in Monthly Notices of the Royal Astronomical Society on May 28, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

Volatile solar activity rapidly increases the amount of space debris falling to Earth, such as old satellites and rocket stages, creating challenging-to-predict hazards for space launches, according to new research from India’s Vikram Sarabhai Space Center.

Low Earth orbit, the region 400 to 2,000 kilometers above the surface, where essential satellites governing GPS and communications infrastructure reside, is also home to a tremendous and growing amount of space debris, which must be carefully monitored to ensure launch safety for space missions.

According to a new paper published in Frontiers in Astronomy and Space Sciences, solar activity is increasing the instability of this floating trash, potentially triggering a domino effect that threatens multiple satellites.

Monitoring Space Debris

Capturing space debris and removing it from orbit remains a nascent subfield within the broader space economy, making monitoring essential for safe launches.

“Here we show that space debris around Earth loses altitude much faster when the Sun is more active,” said co-author Ayisha M. Ashruf. “For the first time, we find that once solar activity passes a certain level, this loss of altitude happens noticeably more quickly. This observation is expected to be key for planning sustainable space operations in the future.”

Solar activity follows an 11-year cycle, during which the Sun passes through low- to high-intensity phases that are known to produce violent space weather. Previous work has focused on how space weather can cause electrical disruptions that can be dangerous to essential satellite infrastructure, damaging its onboard electrical systems. Yet in this study, an entirely different problem arises: the effect of space weather on floating space junk physically crashing into active satellites, creating unexpected obstacles to new launches.

Solar Particles

In more active periods, solar flares and coronal mass ejections can hurl heavy doses of UV radiation and charged particles, such as helium nuclei and heavy ions, toward the Earth. This has the effect of heating our planet’s thermosphere and increasing drag on near-Earth objects as atmospheric density rises. Under that increased resistance, objects begin to slow their orbits and fall at much greater rates.

For their research, the Vikram Sarabhai team reviewed 36 years of historical data covering the 22nd through 24th solar cycles. Over that period, they tracked 17 space junk objects at altitudes ranging from 600 to 800 kilometers through their 90- to 120-minute orbits, until they eventually burned up in the atmosphere.

These inanimate objects were completely at the mercy of their thermosphere density-drive orbital decay as they fell out of the sky, as they lacked the ability to alter their own orbits as active satellites do. According to the researchers, space junk is an excellent way to study the relationship between atmospheric drag and solar activity.

Space Debris Danger Zone

In their analysis, the researchers identified a crucial threshold at which space junk begins to fall much more rapidly, around two-thirds of the way through the sunspot cycle. 

“This threshold doesn’t seem to be tied to a fixed value of solar radiation, but rather to how close the Sun is to its peak activity,” Ashram said. “Around this point, the Sun produces more intense EUV radiation, which may be driven by changes in solar processes that become stronger near the peak.”

The researchers say their work will be crucial to future space missions, as planners will now have to recognize and mitigate the increased dangers of launching during solar activity above that two-thirds threshold. Additionally, planners should consider the effect of solar activity on thermospheric drag when planning mission length and fuel loads to ensure successful completion.

They were also quick to note that this work highlights how meaningful even historical space objects can be to modern research, with some of the space debris they tracked having origins with launches all the way back in the 1960s.

The paper, “Characterizing Solar Cycle Influence on Long-Term Orbital Deterioration of Low-Earth Orbiting Space Debris,” appeared in Frontiers in Astronomy and Space Sciences on May 6, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.