In contrast to most astrophysical situations where information about hot plasmas can be obtained only from emission and absorption spectra, often without spatial resolution, plasmas in the solar system in many cases provide us with the opportunity to make direct, in situ measurements. Such plasmas, notably the solar wind and the plasmas contained in the magnetosphere of the earth, Jupiter, and other planets, must be heated by processes which are in many cases similar to those occurring in astrophysical plasmas and their behaviour should also be to some extent similar. It is therefore interesting and instructive to be able to compare our observations and understanding of these accessible solar system plasmas with those found elsewhere in the universe which are not so easy to observe in detail. This might provide us with some new ideas and perspectives on the nature and behaviour of hot plasmas in general and also an opportunity to test some of our ideas against “ground truth”.