Magnetic field strength on the near side of the Moon We’ve known since the beginning of the space age that the Moon has no global magnetic field. Before we returned samples from the Moon, this was thought to be well understood – compared to Earth, the Moon is a small body (1% the mass) and it rotates very slowly (almost 30 times slower). The large magnetic field of Earth is generated in its very large, rapidly rotating, molten nickel-iron core. This process, called a core dynamo, is thought to be the principal explanation for global magnetic fields in planets throughout the Solar System. Thus [...]
