How does the moon protect the earth

How the moon protected the earth's atmosphere

The moon's magnetic field once played a crucial role in the earth's atmosphere. It is currently a thousand times weaker than Earth's, but that wasn't always the case - around four billion years ago it was about as strong as Earth's today. With the help of simulations, scientists have now shown that the magnetic fields of the earth and moon at that time possibly overlapped and together contributed to the preservation of the earth's atmosphere. As the researchers report in the journal “Science Advances”, the earth's magnetic field alone could not have protected the atmosphere from the solar wind - the charged particles that constantly hit the earth from the sun.

United magnetosphere of earth and moon

Since the first moon landing in 1969, researchers have examined numerous rock samples collected on the moon. More recent analyzes of the samples showed that the moon's magnetic field around four billion years ago was stronger than previously known. At that time the earth was about 600 million years old and the moon about 500 million years old. In addition, the earth and moon were much closer to each other: only about 115,000 kilometers instead of the current 384,000 kilometers separated the two heavenly bodies.

Based on the new results, James Green from NASA and his colleagues simulated the magnetospheres of the earth and moon - the areas in which their respective magnetic fields predominate. The simulations show that a common magnetic field formed around the earth and the moon at that time. According to the researchers, this combined magnetosphere may have deflected the then stronger current of charged particles from the sun and thus protected the earth's atmosphere.

Without the strong lunar magnetic field, the earth's atmosphere would probably not have withstood the solar wind and would have become thinner. This would have made the conditions for life on earth much more difficult. In the coming years, researchers are planning new missions to the moon with the Artemis space project. Among other things, samples are to be collected at the south pole of the moon. Green and his colleagues hope that the new samples will also confirm their simulations of the combined magnetosphere of the earth and moon and their influence on the earth's atmosphere.