Heliospheric magnetic fields and plasmas

Twenty years ago, Mariner 2 was launched and provided the first extensive and definitive measurements in the interplanetary medium. Parker completed his book “Interplanetary Dynamical Processes” [Parker, 1963] at that time, giving a sound theoretical basis for the interplanetary studies which followed. Ten years ago, Pioneer 10 was launched and initiated the exploration of “deep space”. Hundhausen's book “Coronal Expansion and Solar Wind” [Hundhausen, 1972] was published then, and it organized the first decade of interplanetary observations in the framework of supersonic gas‐dynamics.