Around 2.8 billion years ago, something activated and then deactivated the Moon's magnetic field.

In the past, the Moon had a magnetic field similar to that of Earth. However, unlike our planet, the Moon's inner core solidified over time, leading to the disappearance of its magnetic field. Before it vanished completely, it experienced a revival for a period, as noted by IFLScience.

These conclusions were drawn by scientists based on samples of lunar regolith brought back to Earth during the Chang'e 6 mission. This mission was the first to successfully return soil samples from the far side of the Moon.

The spacecraft landed on June 1, 2024, within the Apollo crater, which has a diameter of 537 kilometers. This crater is located in an even larger depression – the South Pole-Aitken basin. This region is of great interest to scientists who are trying to understand the Moon's past.

The Chang'e 6 mission returned over 2 kg of material to Earth, dating back approximately 2.8 billion years. Analyzing this material provided insights into volcanic activity on the Moon and offered unexpected clues about its magnetic field.

Previous studies indicated that the Moon's magnetic field gradually weakened, with a significant drop occurring around 3.1 billion years ago. Consequently, researchers believed that 3 billion years ago, the Earth's satellite's magnetic field was very weak before it completely disappeared.

However, the sample from Chang'e 6 revealed that around 2.8 billion years ago, the Moon's magnetic field strengthened to between 5 and 21 microteslas. For comparison, this is about 10-40% of Earth's magnetic field today and significantly stronger than the Moon's magnetic field 3.1 billion years ago.

Scientists suggest that somehow the weakening of the Moon's magnetic field reversed. The team hypothesized that between 3.5 and 2.8 billion years ago, some changes occurred on the satellite, causing the magnetic field to fluctuate.

Such changes could have been triggered by a magmatic ocean that existed within the Moon for a time. Another theory posits that this resulted from interactions between various rotational forces of the Moon. It is possible that both factors played a role, including the crystallization of the Moon's core.

As a reminder, The Moon formed much earlier than previously thought. Scientists believe that the Moon appeared at least 150 million years earlier than previously estimated.