File photo of an image of the Sun captured by Aditya-L1 during the May solar storm. | Photo credit: SPECIAL ARRANGEMENT
Observations and measurements made by India’s first solar mission, Aditya-L1, have helped decode unusual geomagnetic disturbances at dawn during severe solar storms.
Geomagnetic storms are large disturbances in the Earth’s magnetic field caused by changes in the solar wind – a continuous flow of charged particles released from the Sun.
“When a sudden increase or decrease in solar wind pressure hits the Earth’s magnetic shield (magnetosphere), it can cause sharp changes in the magnetic field,” the Indian Space Research Organization (ISRO) said.
During the peak phase of solar cycle 25, two very intense geomagnetic storms occurred on May 10 and October 10, 2024.
These storms produced large-scale magnetic disturbances and spectacular auroras that were visible even at unusually low latitudes.
Scientists noticed a particularly striking feature during both storms in the form of an unusual pattern in the response of the Earth’s magnetic field. Under normal circumstances, when the dynamical pressure of the solar wind suddenly increases, most low-latitude regions of the Earth experience a positive (enhanced) magnetic perturbation.
When the pressure suddenly drops, a negative (reduced) magnetic disturbance is seen.
“However, during these two severe storms, scientists observed magnetic field disturbances of opposite polarities in the dawn sector. Remarkably, this anomalous behavior was not observed at other stations that were at different local times,” ISRO said.
He further reported that during the May 10 event (during a sudden increase in the dynamic pressure of the solar wind), most low-latitude regions showed positive (enhanced) magnetic perturbations, but dawn-side stations experienced negative (reduced) perturbations.
“During the October 10 event (during the sudden drop in pressure), most low-latitude areas showed a decrease, but stations on the dawn side saw an increase,” it said.
Using particle observations and field measurements from Aditya-L1 and combining them with measurements from a large global network of ground-based magnetic field measurements, scientists from various academic circles (led by the Indian Institute of Geomagnetism, Mumbai) in collaboration with ISRO scientists identified these unusual signatures.
“The study reveals that these unusual dawn-side magnetic disturbances are most likely caused by a special type of cosmic current that is normally confined to aurora (high latitude) regions. During very strong storms, when the Earth’s magnetosphere is strongly compressed, such auroral current systems penetrate into lower latitudes and extend much further equatorward than usual – but especially in the ISRO sector.
He further added that this explains why stations at low latitudes near dawn recorded magnetic disturbances opposite to those observed at similar latitudes elsewhere around the world.
“Understanding how the Earth’s magnetic field responds to sudden changes in the dynamic pressure of the solar wind is important because such rapid magnetic variations can affect technological systems such as satellites, navigation systems, power transmission networks, etc.,” the space agency said.
Combined observations from the Aditya-L1 spacecraft and global ground-based magnetometer networks have provided new insights into how extreme solar wind conditions can alter the normal pattern of geomagnetic disturbances, particularly near dawn local times during intense geomagnetic storms.
Published – 20 Feb 2026 20:13 IST