Researchers from the Massachusetts Institute of technology and Rutgers University found that the ancient magnetic field of the moon was generated giant Dynamo, similar to the earth. To such conclusion scientists have come, having determined that the magnetism of the satellite lasted for a billion years longer than previously thought. Article with the results of scientific work published in the journal Science Advances.
Experts analyzed samples of lunar rocks collected during the mission "Apollo-15". It turned out that they formed 1-2,5 billion years ago in the presence of a relatively weak magnetic field, the induction of which was five microtesla (T). This is about 10 times weaker than the Earth's magnetic field, but 1000 times stronger than the fields in interplanetary space. However, 3-4 billion years ago, the magnetism of the Moon was two orders of magnitude stronger.1.*
Discovery allowed to determine the mechanisms that led magnetic Dynamo in action. First, the field was maintained by rotation of the metallic core. In the early stages of its existence, the Moon was close enough to Earth so gravity last worked on the bowels of the satellite and fixed them in motion. For three billion years, however, the Moon is distant from the planet that has greatly reduced the impact of the latter.
Then comes into action another mechanism that is characteristic of the Earth itself. - The satellite slowly began to cool down, giving rise to convection, where warm layers of substances out, and cool down. The flow of molten metal rocks twisted by the Coriolis force, creating electric currents that, in turn, generate a magnetic field. According to the principle of the mechanism is reminiscent of Dynamo running in the opposite direction.
Dynamo — a device to generate electricity that uses magnetic field and a rotating coil inside of it. The energy of motion is thus transformed into direct current.