The Middle Corona and the Origins of the Solar Wind

Although the solar wind has been characterized in the heliosphere and outer corona using both remote sensing and in situ observations, connecting the signatures we observe in these regions back to the Sun requires observations of the Middle Corona, between about 1.5–6 solar radii. Recent experimental off-point campaigns using the GOES Solar Ultraviolet Imager (SUVI) have revealed the structure, dynamics, and long-term evolution of this region more completely than any previous observations. When coupled with global MHD models, these observations have illuminated the complex topology of the middle corona and its influence on the evolution of the structure of the solar wind. New SUVI observations have uncovered the influential role of the global magnetic structure of the middle corona in governing the behavior of the solar wind on multiple scales, by directly imaging important topological features like the S-web. These observations have also served as key pathfinders for a wide range of new and future observatories specifically geared towards the middle corona, from the extreme ultraviolet Full Sun Imager on Solar Orbiter; to the formation-flying ASPIICS coronagraph on PROBA3 and SunCET EUV imager, both currently in development; to the proposed COronal Spectrographic Imager in the EUV (COSIE) wide-field-of-view EUV spectroscopic imager and ground-based COronal Solar Magnetism Observatory (COSMO). Here, we present these new observations from SUVI and other instruments and discuss their implications for our understanding of the solar corona as a globally-connected system. We then examine some prospects for additional observations that hold the potential to reveal the integral role of the middle corona to understanding the origins of both the solar wind and solar eruptions in even greater detail.