Experimental physicists from SAS detected one of the strongest solar storms of the year
On the first day of June, a strong geomagnetic storm occurred, caused by a solar flare and the subsequent coronal mass ejection (CME) directed toward Earth. Auroras were observed in many parts of the world — even at lower latitudes than usual. One example is an aurora captured by a webcam in San Diego, California. The event was also detected by experimental physicists from SAS.
“At the moment of the coronal mass ejection, a new magnetic field source was created in the solar system. The closer the plasma cloud is to Earth, the stronger the shielding effect of its magnetic field on Earth, resulting in a decrease in the neutron monitor count. The maximum decrease is observed when the plasma cloud passes near Earth and starts to trigger the geomagnetic storm and other space weather effects. As the cloud moves away from the solar system, the intensity of galactic cosmic radiation gradually increases again,” explains the team from the Department of Space Physics at the Institute of Experimental Physics of SAS.
Although auroras were not observed in our region, physicists can still study interesting physical details of the event using the SEVAN systems and the neutron monitor located at Lomnica peak. These instruments were developed to monitor primary and secondary fields of cosmic ionizing radiation.
“The plasma cloud travels at speeds of roughly up to 1000 km/s, but the ‘envelope’ of the magnetic field surrounding the plasma propagates at the speed of light. Since galactic cosmic radiation consists mainly of charged particles, this envelope begins to deflect them outward from the solar system well before the plasma cloud itself reaches Earth, causing a decrease in the observed count of this radiation on Earth. This phenomenon serves as an early warning of the effects that will occur when the plasma cloud passes near Earth,” explains the team.
This mechanism could be used, for example, for early detection of solar mass ejections, because the decline in the galactic component is detected before the plasma reaches Earth. This gives humanity time to prepare for geomagnetic storms, which could otherwise cause serious damage to telecommunications equipment and power grids.
Source: Team from the Department of Space Physics, Institute of Experimental Physics of SAS.
Further descriptions and explanations:
The figure below shows the neutron monitor count before and after the recorded event. As can be seen from the image, solar material began to interact with galactic cosmic ray particles coming to Earth from deep space on June 1, 2025, shortly after midnight, and gradually caused a 15% decrease in the recorded count of secondary neutrons from galactic cosmic radiation. Returning to normal after such an event typically takes several days to a week.