Abstract

The solar atmosphere is heated to millions of Kelvin, which is several orders of magnitude hotter than the visible solar surface below. This hot atmosphere is a plasma, and flows outwards, forming a super Alfvénic solar wind that defines the heliosphere. The solar wind is comprised of structures across a range of scales, with complexity among the structures due to a competition between those structures that are imposed and injected directly from the solar atmosphere, and dynamical evolution as the solar wind flows outwards. There have been remote observations of the solar corona for centuries, and in situ measurements of the solar wind for almost 60 years. Computer simulation capabilities have commenced, and simulation techniques of the cross-scale and cross-regional coupling continue to advance. Yet there are longstanding, major unsolved pieces of this puzzle, involving universal physical processes such as magnetic reconnection, turbulence, and waves. In this talk, we discuss these grand challenge questions and discuss progress and future prospects with recent result from Parker Solar Probe, and Solar Orbiter, as well as the expected results from the upcoming Polarimeter to Unify the Corona and Heliosphere mission.