Long-Term Particle Fluence Distributions and Short-Term Observations

The cosmic environment of Earth directly or indirectly influences conditions for terrestrial life. Cosmic influences include increased fluxes of gas, dust, comets and asteroids, as well as energetic particles and electromagnetic radiation of various energies. The main emphasis of this paper is on the radiation conditions and their variation, together with possible changes in the protective shields or "cocoons" that usually mitigate the dangers of external effects acting on terrestrial life. It is pointed out that the efficiency of protective shields against various kinds of external influences is vastly different, and in some cases their presence may even enhance the detrimental effects. The Sun, the most important pre-condition for terrestrial life, is also discussed as a potential source of danger.