Colloquium: Comprehending our local plasma universe from spacecraft measurements
In the realm of our Local Plasma Universe, the Sun is the primary source of light and heat, supporting life and climate on Earth. The Sun continuously emits magnetized plasma, the solar wind, whose two main components are the fast wind streams originating from coronal holes and the slow wind streams – nearby helmet streamer belts. Occasionally eruptive events such as coronal mass ejections (CMEs) send into space massive amounts plasma and magnetic flux. All these components mix as they propagate and expand away from the Sun, forming a very structured and turbulent plasma flow that interacts with planetary environments. We have learnt a great deal about these interactions from the spacecraft missions sent to various targets in space to sample in-situ the electromagnetic field and plasma properties. However, still a great deal is unknown. I will present some advances in understanding the physics of CMEs, including modeling their large-scale properties, examining their interactions with the solar wind and exploring the generation of small-scale turbulence that leads to energy dissipation and heating. The understanding of plasma heating necessitates the estimation of gradients from multi-point observations, which are readily available in the terrestrial magnetosheath, but can be also utilized as one-point proxies in the solar wind. We find that dissipation and plasma heating occur at coherent structures, such as current sheets, in close correspondence with recent numerical simulations of plasma turbulence.