Fig. 1. Plasma flow and magnetic field evolution following a basin-forming impact on the Moon.
Snapshots are extracted at 10, 50, 150, and 300 s after impact in the plane containing the impact vector (−z direction), solar wind flow (+z direction), and the IMF (+x direction). The impact location is at (x, y, z) = (0, 0, 1) Rm. The left panels show the plasma density (color contours) and velocity (white arrows, scaled to the speed and pointing in flow direction). The middle panels show the magnetic field magnitude (color contours) and vector (black arrows, scaled to magnitude and pointing in field direction). The right panels show diagrams highlighting the factors controlling the field evolution at each snapshot. The arrows marked by U and B are the solar wind velocity and IMF direction, respectively. The full evolution can be viewed in the Supplementary Materials (movie S1).