Scientists at MIT have proposed a new theory to explain the moon’s mysterious magnetic anomalies, suggesting that a combination of an ancient weak magnetic field and a large impact could have temporarily created a strong magnetic field on the far side of the moon.
A Brief Amplification of the Moon‘s Weak Magnetic Field
The Mystery of the Moon‘s Magnetism
For decades, scientists have puzzled over the moon‘s missing magnetism. Despite having no inherent magnetism today, samples from the surface of the moon and global measurements by orbiting spacecraft show signs of remnant magnetism in surface rocks, particularly on the far side of the moon.
The Moon's magnetic field is relatively weak, about 1% of Earth's.
It was once thought to be non-existent due to Apollo-era spacecraft measurements.
However, recent studies using data from NASA's Lunar Prospector mission revealed a surprisingly complex magnetic field.
This field is likely the result of interactions between the lunar interior and the solar wind.
The Moon's magnetism is also believed to have played a crucial role in its geological history, particularly in the formation of its crust.
A New Theory Emerges
MIT scientists may have solved the mystery with a new theory that proposes a combination of an ancient, weak magnetic field and a large impact could have temporarily created a strong magnetic field concentrated on the far side of the moon. According to their study published in Science Advances, researchers simulated a large impact to the moon‘s surface, generating a cloud of ionized particles that briefly enveloped the moon.
The Role of Plasma
The team found that as the plasma cloud arose from the impact, some of it expanded into space while the rest streamed around the moon and concentrated on the opposite side. There, the plasma compressed and briefly amplified the moon‘s weak magnetic field. This entire process would have been incredibly fast, lasting around 40 minutes.
Plasma is one of the four fundamental states of matter, characterized by its high temperature and ionization.
It is composed of ions, free electrons, and neutral atoms or molecules.
Plasma can be found in stars, including our sun, as well as in lightning and neon signs.
On Earth, plasma is used in medical treatments such as blood transfusions and cancer therapy.
It is also used in industrial processes like cutting and welding metals.
A Pressure Wave and Shock
Another impact-related effect played a crucial role in this theory. Researchers found that an Imbrium-scale impact sent a pressure wave through the moon, similar to a seismic shock. These waves converged on the other side, jittering surrounding rocks as they briefly unsettled their electrons – the subatomic particles naturally orienting themselves to any external magnetic field.
Testing the Theory
The researchers suspect that this combination of a dynamo plus a large impact, coupled with the impact’s shockwave, is enough to explain the moon‘s highly magnetized surface rocks – particularly on the far side. Direct sampling of the rocks for signs of shock and high magnetism could provide further evidence.
Implications
This new theory suggests that the moon‘s missing magnetism may be a result of both an internal dynamo and external impacts. By understanding this phenomenon, scientists can better comprehend the history of the moon and its interactions with space.
The moon is Earth's only natural satellite, orbiting our planet at an average distance of about 239,000 miles (384,000 kilometers).
With a diameter of approximately 2,159 miles (3,475 kilometers), the moon is the fifth-largest satellite in the solar system.
The moon's surface is covered with craters, mountains, and lava flows , formed by asteroid impacts and volcanic activity over billions of years.
The moon has played a significant role in Earth's tides, stabilizing our planet's axis, and influencing the development of life on Earth.
