These and other similar cyclical changes are thought to be responsible for ice ages (see Milankovitch cycles). By contrast, the obliquity cycle for Mars is much more extreme: from 15° to 35° over a 124,000-year cycle. Some recent studies even suggest that over tens of millions of years, the swing may be as much as 0° to 60°.[2] Earth's large Moon apparently plays an important role in keeping Earth's axial tilt within reasonable bounds; Mars has no such stabilizing influence and its axial tilt can vary more chaotically.