Azernews.Az

By Alimat Aliyeva

An international team of scientists has proposed a new explanation for a long-standing mystery in lunar geology: why some rock samples brought back by the Apollo missions show evidence of a strong magnetic field on the Moon in the past. A study published in the journal Nature Geoscience suggests that the Moon may have had a powerful magnetic field, but only for short periods, AzerNEWS reports.

Today, the Moon’s magnetic field is extremely weak and localized, unlike the Earth’s global and stable magnetic field. However, lunar rocks about 3.5 billion years old indicate that in the past, the Moon’s magnetic field could have been much stronger, sometimes even comparable to Earth’s current field. This has puzzled scientists for decades, as the Moon is much smaller than Earth and lacks the internal energy sources necessary to sustain such a field.

Researchers from the University of Oxford suggested that the strong magnetic signals in the rocks might have resulted not from a long-lasting field, but from rare, short-lived bursts of magnetic activity.

The team re-examined so-called mare basalts, volcanic rocks formed on the Moon’s ancient lava plains. They found that the most strongly magnetized samples contained higher amounts of titanium.

Using computer simulations, the researchers showed that melting of titanium-rich rocks near the core-mantle boundary could increase heat flow from the core. This, in turn, could temporarily activate the dynamo process—the mechanism that generates a magnetic field.

Interestingly, the same processes likely caused eruptions of titanium-rich lava, samples of which were later collected by the Apollo astronauts. In other words, the rocks themselves may have “recorded” these brief but intense episodes of magnetic activity.

Geologist John Wade noted that conclusions may be partially biased due to the limited number of samples. He offered an analogy: if aliens had visited Earth only a few times and collected rocks from just one area, their understanding of our planet would likely be very inaccurate.

According to this new theory, periods of strong magnetic fields on the Moon may have lasted only a few thousand years—a blink of an eye in geological terms.

Despite the limited data, scientists believe future missions, including NASA’s Artemis program, could help test this theory. New rock samples will allow researchers to reconstruct the Moon’s magnetic history more accurately and may even reveal other secrets about its internal structure.

On Earth, the magnetic field not only shields us from the solar wind but also helps animals navigate. Scientists speculate that if the Moon had maintained a strong magnetic field for longer periods, its surface might have looked very different—better protected from cosmic radiation and micrometeorite impacts.