Rust, on the moon? Scientists say they were shocked to find it lurking on the moon's polar surfaces, Space.com reports. "At first, I totally didn't believe it. It shouldn't exist based on the conditions present on the moon," says NASA scientist Abigail Fraeman, co-author of a study on the find. "But since we discovered water on the moon, people have been speculating that there could be a greater variety of minerals than we realize if that water had reacted with rocks." But rust is only created when iron touches water and oxygen, and the moon's paltry atmosphere can't provide enough of the latter. So lead author Shuai Li worked with NASA scientists for months to devise a fresh theory, CNN reports.
They knew Earth's magnetic field stretches far enough for the moon to enter its tail for days at a time. Maybe that also allows oxygen to move from the Earth to the moon, mix with lunar water molecules, and form rust on its near side, the study says. But mysteries remain: Why are smaller amounts of iron also forming on the far side of the moon, where Earth's oxygen shouldn't reach? And how is the moon's water interacting with rock? Clearly, there's more to learn: "This discovery will reshape our knowledge about the moon's polar regions," Li says in a press release. "Earth may have played an important role on the evolution of the moon's surface." (Meanwhile, NASA has patented a cheaper way to reach the moon.)