Learn how surface features on the Moon indicate it is geologically active in this interactive activity adapted from NASA. In 2010, the Lunar Reconnaissance Orbiter captured images of lobate scarps, geological features that form when two surfaces at a thrust fault are pushed together; these features indicate that the Moon is shrinking. In 2012, new observations showed surface features, called graben, which form where the crust has pulled apart; these features are evidence that the Moon is expanding in some places. These discoveries suggest that the Moon is still geologically active and challenge ideas about how the Moon formed and evolved. This resource is part of the NASA Planetary Sciences Collection.