Mercury’s Magnetic Field and Exosphere as Seen by MESSENGER
To conclude our survey of Mercury as understood near the end of the MESSENGER era, we now look at Mercury’s magnetic field, the magnetosphere that it dominates, and its interaction with the solar wind and Mercury’s surface. Charged particles from the Sun (the solar wind) and ions arising from Mercury’s surface are controlled by the magnetic field lines in Mercury’s environment, whereas neutral atoms escaping from Mercury’s surface belong to its exosphere and their motion is independent of magnetic fields. Clearly the magnetosphere and exosphere occupy overlapping domains. We will look at each in turn, and at their relationships with Mercury’s surface.