Scientists have compiled the first global map of fault ridges in the Moon 's maria , revealing that lunar tectonic activity across these dark basalt plains is far more widespread than previously thought. Not only that, some of the ridges have been dated to just a few tens of millions of years old – relatively recent, in geological terms. It's the clearest picture yet of how the Moon as a whole is still slowly shrinking, wrinkling up its surface like a drying-out old apple. The findings suggest