Evolution of PSP’s magnetic connectivity and Alfvén radii over solar cycle 25. Top left: Longitudinally averaged magnetic field of the Sun (magnetic butterfly diagram) with dashed (monthly) and solid (monthly smoothed) lines following the reversal of the dipolar component of the Sun’s magnetic field. The magnetic field polarity measured by PSP (markers) and its connectivity in latitude (vertical field lines) from PFSS modelling are shown for each encounter. Bottom left: Fraction of open magnetic field lines at the solar surface from PFSS modelling with a fixed source surface at 2.5 R_⊙. The reversal of the dipole is shown as above. Markers show the sources of the solar wind (from the field lines in the upper-left panel) and are coloured by the size of the Alfvén surface. Right: Same as the left panels but now showing structure in Carrington longitude using latitudinally averaged data.