Super Solar Storms: Most Particles Come from Earth
When a solar storm occurs, our Sun ejects high-energy plasma and intense radiation into space. These bursts of radiation and charged particle clouds can lead to geomagnetic storms upon reaching Earth. As energetic particles penetrate the upper atmosphere, they create stunning auroras even in mid-latitude regions, but they can also have severe consequences.
The Mystery of Ring Current Particles
Typically, the Earth’s magnetic field deflects a significant portion of particles emitted by the Sun. Energetic ions accumulate in a region called the ring current, which exists thousands of kilometers above the equator. In this area, negatively charged electrons travel eastward while positively charged protons and heavier ions move westward around the Earth. During intense geomagnetic storms, some particles manage to breach this electromagnetic barrier and penetrate into the Earth’s ionosphere.
The precise composition of the ring current and the extent to which strong solar storms contribute to it had been a contentious issue until recently. A breakthrough came from a research team led by Naritoshi Kitamura from Nagoya University. The Japanese Arase satellite was traversing the Earth’s ring current during one of the strongest solar storms recorded on May 10 and 11, 2024, allowing researchers to identify the origins of different particles.
The ring current comprises charged particles that circle the Earth high above the equator. — © ERG Science Team
85 Percent of Ions Originate from Earth
“This marks the first simultaneous observation of ring current ions and solar wind during such a powerful geomagnetic storm,” explained Kitamura. The data collected by the Arase satellite confirmed the incredible intensity and energy of this super solar storm. “Just before the peak of the storm, Arase detected a 40% reduction in magnetic field intensity at an altitude of 16,000 kilometers,” reported Kitamura, highlighting the extent to which the normally stable Earth’s magnetic cage was disrupted.
Surprisingly, the particle measurements revealed that the solar storm contributed far fewer particles to the ring current than anticipated. Instead, a substantial amount of high-energy ions were propelled upward from Earth’s atmosphere into the ring current. “The data were clear: approximately 85 percent of the ions were oxygen ions from our own planet’s ionosphere,” Kitamura noted. In contrast, solar particle streams contributed only minimally to the energy density of the ring current.
Heavy Ions and Their Potential Consequences
These unexpected results shed new light on what happens during a super solar storm high above us. Contrary to prior assumptions, the electromagnetic ring current during such extreme geomagnetic events is not mainly filled with light protons from the solar wind. Instead, it is enriched with much heavier and more energetic oxygen ions from Earth’s ionosphere. “This emphasizes the central role of ionospheric upflow processes that generate, accelerate, and propel ions to high altitudes,” the researchers concluded.
This influx of heavy ions might also elucidate why these and other “super solar storms” can significantly weaken the Earth’s magnetic field and push the entire ring current closer to the planet. The increase in heavy, energetic ions from the atmosphere intensifies magnetic disturbances and alters the flow of particles in these elevated regions above Earth.
The findings from Kitamura’s team not only enhance our understanding of solar storms but could also have implications for the design of satellites and space missions. As we continue to explore the complexities of solar-terrestrial interactions, the insights gained from these studies will be crucial for protecting our technological infrastructure from the potentially disruptive effects of super solar storms.
For more information, refer to the original study by Naritoshi Kitamura et al. in Science Advances (2026). View the research here.
