Despite its slow revolving, Mercury has a relatively strong magnetic field, with a magnetic field strength 1% as strong as the Earth’s. It is potential that this magnetic field is generated in a manner similar to Earth’s, by a dynamo of circulating liquid core material. However, scientists are uncertain whether Mercury’s core could still be liquid,although it could perhaps be set aside liquid by tidal effects during periods of high orbital eccentricity. It is also probable that Mercury’s magnetic field is a remnant of an earlier dynamo effect that has now ceased, with the magnetic field becoming “frozen” in solidified magnetic materials.
Mercury’s magnetic field is physically powerful sufficient to deflect the solar wind around the planet, that creates a magnetosphere within which the solar wind does not go through. This is in difference to the situation on the Moon, which has a magnetic field too weak to stop the solar wind impacting on its surface and so lacks a magnetosphere.