*Context.* A complex and long-lasting solar eruption on 17 April 2021 produced a widespread Solar Energetic Particle event (SEP) that was observed by five longitudinally well-separated observers in the inner heliosphere covering distances to the Sun …
*Aims.* The first relativistic solar proton event of solar cycle 25 was detected on 28 October 2021 by neutron monitors (NMs) on the ground and particle detectors on board spacecraft in near-Earth space. This is the first ground-level enhancement …
*Context.* Sheath regions ahead of coronal mass ejections (CMEs) are large-scale heliospheric structures that form gradually with CME expansion and propagation from the Sun. Turbulent and compressed sheaths could contribute to the acceleration of …