The Sun interacts with planetary bodies through radiation and solar wind, which vary on, time scales ranging from minutes to glacial cycles. Sun continuously provides radiation to the Earth with considerable variation in the spectral density, which is sporadically modified by flares that affects the Geospace. The quasi-steady flow of the solar wind is also modified by coronal mass ejections (CMEs) causing geomagnetic storms, impacts the technological assets and health of astronauts.
Though prompt penetrating electric fields (PPEF) are infrequent, they play a crucial role in modifying the ionosphere by modifying the global electric fields. The precipitating solar energetic particles (SEPs) affect wave propagation, winds and temperatures in the northern hemisphere winter stratosphere. Occasionally during winter, the interaction of waves with polar circulations induces phenomena known as sudden stratospheric warming (SSW) episodes; which have significant ramifications as far as the global middle and upper atmosphere is concerned. The impact of SSW events is not limited to altered patterns of Equatorial Spread F (ESF) but ranges in a variety of thermosphere-ionosphere processes like circulation changes and reversal of the equatorial electrojet (EEJ).
Solar–Terrestrial Interactions (STI) Research focuses on the coupling between different regions in near-earth Geospace (Mesosphere, Thermosphere, Ionosphere, and Magnetosphere) as well as on Earth affecting solar transient events and solar activity.