Peppered around lava flats and mountaintops all over the moon are strange sinuous shapes known as lunar swirls. Their winding, dusty curves are brighter than the surrounding area and, so far, their formation remains a mystery to scientists.
“They look like someone took a white paintbrush and painted across the moon,” says Catherine Neish, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. She helped organize the 2011 Lunar Swirls Workshop Without Walls, an online conference dedicated to these puzzling features. At the meeting Sept. 7, scientists presented new data that may help finally determine the cause of the swirls.
Known about since the Renaissance, lunar swirls came under increased scrutiny after orbiting satellites in the 1960s noticed that they tended to be associated with magnetic fields. Unlike the Earth’s large global magnetic field, these lunar magnetic fields are small local phenomena that are strewn more or less randomly on its surface. Wherever researchers find lunar swirls, they find these magnetic fields.
