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Center for Nonlinear Studies |
The Sun is the closest steady-state reliable fusion reactor that directly impacts the humankind, and will continue to do so for a while longer. The sphere of influence of the Sun on the plasma environment in the greater cosmos, the Heliosphere, includes the Earth and all the rest of the planets in the Solar System. This sphere of influence is determined by the solar wind, a quasi-steady flow of plasma particles away from the Sun that interacts with the interstellar medium to determine the boundary of the Heliosphere. The existence of the solar wind was predicted and soon thereafter confirmed with direct observations in the late 1950s; yet, our understanding of the observed properties of the solar wind remains limited. What we do know, however, is that its origin lies in the solar corona, a particularly hot region of space within several solar radii of the much colder visible surface of the Sun. Why is the corona much hotter than the surface? That's another mystery that we have some clues to, but not yet any conclusive evidence to resolve. In this lecture, I will attempt to give an overview of our current state of knowledge of the plasma conditions in the Heliosphere, what we do and don't understand about these plasma conditions, and how the dynamic solar activity can impact the near-Earth space environment.
Host: Tom Intrator