These are strange swirling formations, brighter than the rest of the lunar soil, and found all over the surface of our satellite. Scientists do not yet know how or why they form
It is one of the strangest things that can be seen on the Moon. Brilliant and mysterious marks whose shapes resemble the cream in a cup of coffee, but which extend over tens of km, brighter than the rest, twisting in the form of large eddies protected, moreover, by magnetic fields.
Scientists have been studying lunar swirls for decades, and different theories have been formulated about their origin, but the truth is that these strange formations continue to puzzle astronomers. What can it be? Could they be an unknown consequence of meteorite impacts? Or perhaps the remains of an ancient lunar magnetic field? The truth is that we do not know.
Now, a new study by researchers at the Planetary Science Institute in Tucson, Arizona, has just complicated things even further by revealing that the eddies are not just on the lunar surface, as previously thought, but are related to deep topographic changes. They are, therefore, even more, complex than previously believed. The results of this research have just been published in ‘Geophysical Research Letters.
Lunar eddies vary greatly in shapes and sizes, ranging from a few meters to more than 50 km, and have been found all over the Moon’s surface, including inside many impact craters.
Led by Deborah Domingue, researchers once again tried to solve the mystery by using data from NASA’s Lunar Reconnaissance Orbiter to accurately model elevations around two particular eddies, located in an area called Mare Ingenii. According to the maps, the bright areas of the eddies were, on average, 2 to 4 meters lower than the darkest areas both in and around the eddies themselves.
The same area, explains Domingue, had been analyzed before, “but never at this level of spatial resolution. On larger scales, this correlation is not obvious. It was definitely a surprise.”
Because all lunar eddies seem to be associated with magnetic fields, previous attempts at explanations have focused on how these fields ‘protected’ the soil from erosion by particles from the Sun. “We still think that protecting yourself from the solar wind plays an important role in the formation of lunar eddies -explains the researcher-, but what our analyzes show is that they may not be the only thing at stake and that other processes must be taking place”.
The observed differences in elevation, along with other measures of the size of the dust devil grains, do indeed suggest that these ‘other processes’ are related to the way the dust itself moves across the lunar surface. A fact that until now was not handled and that could hide the key to solving the mystery
Now, Domingue and his colleagues continue to work to extend their analyzes to eddies in other regions of the Moon and find out how moondust grains of different sizes move. Important, scientists say, not only for figuring out how eddies form, but also for any installation or future permanent base on the Moon that wants to avoid being buried by fine lunar sand.
