Our research explored the "shock aurora," caused by the impact of solar wind particles on Earth's magnetic field. On February 26, 2023, we observed this rare event on the nightside, where such observations are difficult. Ground-based cameras revealed new structural features, including undulating and jumping patterns. These results provide fresh insights into the complex interactions between the solar wind and Earth's magnetosphere, enhancing our understanding of space weather effects.

The complete time series of the geomagnetic disturbance index (K) from Norwegian magnetic observatories have been digitized. We compare and discuss the tree methods used to derive the index, finding that each method both have strengths and weaknesses. In total, we present all K-indices derived from Norwegian observatories since the 1930s until today, the used derivation methods and the long, historic time-series as a whole, enabling a critical use for future scientific work.

This paper presents a study of millihertz magnetic pulsations seen in the magnetosphere and on the Earth under quiet space weather conditions. We found that these fluctuations appear in the magnetosphere as soon as disturbances with the same frequency vanish in the solar wind. The results of this work show the possibility of a substorm developing under absolutely quiet external conditions and allow us to assume that these pulsations represent a substorm preparatory phase.

Using the RENU2 rocket and ground-based instruments, we show that significant parts of the blue aurora above Svalbard at the time of launch were sunlit aurora. A sunlit aurora occurs when nitrogen molecules are ionised by extreme UV sunlight and subsequently hit by electrons from the Sun, resulting in blue and violet emissions. Understanding the source of an auroral emission gives insight into the interaction between the Sun and the Earth's upper atmosphere.

Energetic particle precipitation has the potential to change the neutral atmospheric temperature at the bottom of the ionosphere. We have searched for events and investigated a possible correlation between lower-ionosphere electron density enhancements and simultaneous neutral temperature changes. Six of the 10 analysed events are associated with a temperature decrease of 10–20K. The events change the chemical composition in the mesosphere, and the temperatures are probed at lower altitudes.