The colors illustrate differences in elevation on Mars' surface, with the ancient rotation poles indicated (the north polar cap at center shows the location of the present-day pole). Through a phenomenon called true polar wander, Mars' spin axis and poles might have shifted by nearly 3,000 kilometers along the surface sometime within the past 2 or 3 billion years. As this shift occurred, surface topography of the shorelines deformed because spinning planets bulge at their equator. Image courtesy Taylor Perron/UC Berkeley| News Release