Mercury’s Projected Magnetopause Positions in Proton Density-Velocity Space From 1996-2025

In our prior work, we developed and successfully benchmarked the Portable Magnetopause (MP) Model against spacecraft-measured MP standoff positions in two contexts: (1) magnetic field strengths and MP locations at Earth and other solar-system planets with dipolar fields, and (2) the dynamic response of Earth’s MP to coronal mass ejection (CME) impacts. In the present study, we apply the Portable MP Model to Mercury by plotting scaled Earthly hour-averaged spacecraft measurements of solar-wind plasma mass density (x-axis) and velocity (y-axis), with MP standoff distance rendered as iso-contour values (z-axis). The Portable MP Model accurately computes Mercury’s MP position in the nearfield of its modeled best-fit dynamo current ring. As a first-principles approach, rather than a statistical regression, the Portable MP Model provides physically interpretable terms. The governing equations are algebraic, making the model accessible to a broad audience, including professional space scientists and engineers, students from middle school through graduate school, and scientifically engaged members of the public. We present contour plots based on scaled solar-wind hourly data, enabling visualization of MP standoff positions to support discussion of Mercury’s magnetospheric response to past and future CMEs. This study spans five and a half solar cycles (late 1963 through late 2025), providing a long-term perspective that may prove useful for planning spacecraft activities at Mercury.