In this talk we shall discuss the structure and dynamics of the plasma environment of the earth and how it is influenced by the sun and its magnetic field, as has been revealed to us by observations, both remote and in situ, in the past 40 years or so.

After presenting a brief overview of the major historical landmarks in the development of space plasma physics, we shall discuss the structure of the solar plasma and then see, by looking at its interaction with the earth’s magnetic field, how the earth’s magnetosphere and ionosphere are. We shall look into the composition of the earth’s plasma layers. We shall also briefly discuss the behaviour of comets when they come close to the sun.