This open access book serves as textbook on the physics of the radiation belts surrounding the Earth. Discovered in 1958 the famous Van Allen Radiation belts were among the first scientific discoveries of the Space Age. Throughout the following decades the belts have been under intensive investigation motivated by the risks of radiation hazards they expose to electronics and humans on spacecraft in the Earth's inner magnetosphere.

Hannu Koskinen is Professor in space physics at the University of Helsinki. He worked 1981-1987 as a researcher at the Swedish Institute of Space Physics in Uppsala and received his PhD degree from Uppsala University in 1985. During 1987-1997 he held different research positions at the Finnish Meteorological Institute. In 1997 he was appointed as professor in space physics at the University of Helsinki. Years 2010-2013 he was the head of the Division of Geophysics and Astronomy and 2014-2017 the Director of the Department of Physics. He retired in 2018 and continues as a Professor Emeritus.
Hannu Koskinen has been a co-investigator in 11 different space missions. He was a Delegate of Finland in the Science Programme Committee of ESA 2002-2016 and the Chair of the Programme Board of the Space Situational Awareness Programme of ESA 2011-2014. He is a member of the Finnish Society of Sciences and Letters (2005), the Finnish Academy of Sciences and Letter (2006), the International Academy of Astronautics (2009) and Academia Europaea (2017).
Hannu Koskinen has been an author/co-author of about 150 peer-reviewed scientific articles that have been cited about 6000 times. He has published a single-authored monograph "Physics of Space Storms - From the Solar Surface to the Earth", Springer/Praxis, 2011. Furthermore, he has written three textbooks in Finnish (on classical mechanics, classical electrodynamics, space physics) and an English textbook on introductory plasma physics together with Emilia Kilpua (published locally in Helsinki).

Emilia Kilpua (née Huttunen) is Professor in space physics at the University of Helsinki. She received her PhD degree in 2005, after which she worked as a post-doctoral researcher and assistant research scientist at Space Sciences Laboratory of the University of California, Berkeley (2005-2008). 2009-2015 she worked as Academy Research Fellow of the Academy of Finland at the University of Helsinki and was appointed as Associate Professor in 2015. Since November 2020 she is a full professor in space physics. She became a member of the Finnish Academy of Sciences in 2020.
Emilia Kilpua is a group leader in the Finnish Centre of Excellence for Sustainable Space (2018-2023) and the recipient of a Consolidator Grant of the European Research Council (2017-2021). In addition to her scientific activities she has been a very active teacher, being currently the head of Doctoral Programme in Particle Physics and Universe Sciences and a member of the Board of Master's Programme in Particle Physics and Astrophysical Sciences. Her rapidly growing publication list contains about 130 peer-reviewed scientific articles with more than 3500 citations. One of them is an invited article in Living Reviews of Solar Physics of Springer. She has authored the above mentioned introductory plasma physics textbook together with Hannu Koskinen.