Abstract
This study examines a unique heliogeophysical event: X- and M-class solar flares from November 9–11, 2025, accompanied by a coronal mass ejections directed toward Earth. The disturbed state of near-Earth space during the period from November 11–15, 2025, was studied using solar wind parameters. The solar wind proton density during this period showed several spikes, the solar wind velocity increased to 1000 km/s, and a sharp increase in proton temperature was observed. The geomagnetic field was strongly disturbed, with a Kp-index of 9. Minute values of the AL, AU, SYM-D, and SYM-H indexes, as well as two-hourly values of the global electron content, were also used to describe the event. This paper examines physical processes on the Sun, in the interplanetary magnetic field, magnetosphere, and upper layers of the Earth's atmosphere during a unique geocosmic storm, making it interdisciplinary in nature. It has been established that a powerful solar storm in November 2025 caused extreme geomagnetic and negative ionospheric storms.