LROC WAC color ratio 321/415 nm shows little variation due to crater rays. The dark haloed crater, Giordano Bruno, in the upper center is thought to be quite young and thus “immature” and thus still has a distinct UV signature. The most immature material on the Moon as defined by the UV maturity signal are the enigmatic “swirls”. The swirls are likely due to local relatively intense magnetic fields standing off the solar wind and thus protecting mineral grains from the maturing effects of solar wind sputtering. Credit: NASA/GSFC/Arizona State University