Erosion on the Moon is not the same as on Earth. Without an atmosphere or plate tectonics, the lunar surface is covered in impact craters and dust; This dust may hold clues to the magnetic past of our lunar companion. A team of scientists has discovered several dust-covered rocks with a strange reflection in a region of the Moon already known for its features, the Rainer Gumm Lunar Gyre.

Originally mistaken for a crater, Rainer Gamma is actually a flat area that casts no shadows but shines brightly against the vast lunar plain called Oceanus Procellarum. Lunar vortices such as Rainer Gamma are thought to be formed by, or at least associated with, pockets of magnetized rock that deflect particles from the solar wind. The magnetized material is believed to be protected from the solar wind, which darken surrounding areas through chemical reactions and create vortexes visible enough to be seen from Earth.

But other theories suggest that the vortices may have formed through the interaction between magnetic anomalies in the lunar crust and electrically charged fine dust particles triggered by micrometeorite impacts. It is also possible that the vortices and magnetic fields form from clouds of material ejected by comet collisions. To better understand these interactions, planetary scientist Ottaviano Rüsch of the University of Münster in Germany and his colleagues scanned nearly a million images of cracked rocks taken by NASA’s Lunar Orbiter Reconnaissance Orbiter orbiting the Moon.

In the Reiner K crater near the Reiner Gamma vortex, they detected a rock that reflected light in a different way than the dust-covered rocks they had seen before.

“We detected a rock with distinct dark areas in just one image,” explains Rüsch, who led the original 2023 study and the latest study. “This stone was very different from the others because it reflected less light towards the sun than the other stones.”

Its special properties have led researchers to look for dustier rocks like these, using artificial intelligence to sort odd-looking ones by size and reflectance. The algorithm identified nearly 130,000 possibilities, half of which were carefully examined by researchers.

Rocks with lower reflectivity were localized near the Rainer Gamm magnetic anomaly, but not all rocks in the Rainer K crater exhibited strange reflectivity. Therefore, the rocks may have been formed as a result of impact into the crater, but the researchers suspect that their strange reflective properties are greater. It is probably associated with a thin layer of dust deposited on some, but not all, rocks. This powder likely has a unique density, size, or structure, but its properties are still unclear.

The team says the next step is to use their findings to investigate processes that could explain how lunar vortices form, such as the lifting of dust by electrostatic forces or the interaction of the solar wind with patches of magnetism on the lunar surface. Meanwhile, NASA and researchers at the Johns Hopkins Applied Physics Laboratory are preparing to send a lunar lander to visit Reiner Gamma to study magnetic anomalies in the ground. The landing module is planned to be put into operation in 2024.