The dynamic 3D heliosphere: Implications for and new sources of its energetic particles

In recent years, two important aspects of heliospheric physics have emerged: (1) the intrinsic dynamism of the Sun's open magnetic flux and its vast importance for energetic particle propagation and acceleration; and (2) the importance of heliospheric grain populations for the production of energetic particles and anomalous cosmic rays. These new aspects have seeded the discovery of the inner and outer pickup ion sources; the discovery of the outer source of anomalous cosmic rays; the discovery that nearly radial magnetic fields in co-rotating rarefaction regions and associated energetic particle dwells are caused by the motions of open magnetic field footpoints across coronal hole boundaries; the relevance of these footpoint motions for ubiquitous statistical acceleration in slow solar wind and for Favored Acceleration Locations at the Termination Shock (FALTS). Here, we review these emerging discoveries and discuss how their combination is leading to a vastly different and improved understanding of our intrinsically dynamic heliosphere.