Strange Reflective ‘Anomalies’ on the Moon Are a Mystery, Scientists Say

Moon dust has fascinated scientists ever since Neil Armstrong scooped up a vial of the stuff back in 1969. The jagged and statically charged lunar dust provides clues about the moon’s early formation, and tells us about our own geologic history and that of the inner solar system.

Now, planetary scientists have discovered strange "anomalies" in sun-reflecting particles covering meter-wide moon rocks. This research, published in the Journal of Geophysical Research – Planets, could help scientists understand more about the processes that formed and changed the moon’s crust and created unexplained magnetic anomalies. But, for now at least, the odd rocks and dust particles remain an unsolved mystery.

Researchers came across these extraterrestrial dust bunnies while trawling a catalog of images taken by NASA's Lunar Reconnaissance Orbiter spacecraft. They used artificial intelligence to go through the more than a million images and narrow rocks of interest down to around 130,000.

“We keep finding unknown objects in this way, such as the anomalous rocks that we are investigating in this new study," said study co-author Valentin Bickel, from the University of Bern, in a press statement. 

They saw that some rocks around the Reiner K crater—a smaller impact crater near the larger Reiner crater on the western side of the moon—had noticeable dark patches on them. “Normally, lunar dust is very porous and reflects a lot of light back in the direction of illumination,” explained Marcel Hess, an image analyst from the Technische Universität Dortmund. “However, when the dust is compacted, the overall brightness usually increases. This is not the case with the observed dust-covered rocks.”

The team described the rocks’ strange light-reflecting properties using a technique called photometric analysis, which measures how light reflects off objects. 

The researchers suspect that the dust-covered boulders were dispersed as a result of the impact that formed the crater. But not all of the boulders around the Reiner K crater were covered in the perplexing dust.

Just what this dust is and why it only settled on some rocks and not others is still a mystery. The study’s authors theorize it could have to do with the physical features of the moon’s landscape, something about the microscopic structure of the rocks themselves, the static properties of the dust, or the moon’s magnetic fields. The Reiner Gamma region, where the craters lie, is a known magnetic hotspot.

The researchers hope that an upcoming NASA mission to the moon, Lunar Vertex, which will collect samples from the region, will shed some light on the dusty enigma. The mission will also map Reiner Gamma’s magnetic field to help uncover how parts of the moon got their distinctive swirls and bumps. That will help planetary scientists understand not only how the moon formed, but also other astronomical objects with thin or no atmosphere in our solar system.

“Current knowledge of the moon's magnetic properties is very limited. These new rocks will shed light on the history of the Moon and its magnetic core,” said planetary geologist Ottaviano Rüschso, from the Universität Münster, in a statement. 

Plus, understanding how dust swooshes around the moon will be vital for planning future human settlements on the moon, since moon dust is notorious for causing problems for habitats, equipment, and human lungs and brain cells.