This image shows three craters superimposed on one another in the Sirenum Fossae region of Mars, at approximately 28° S, 185° E.
The oldest is the furthest from view, an eroded crater 34 kilometres in diameter. The central crater is about 28 kilometres across, and has yet to be smoothed by erosion. The youngest crater is the small 9 kilometre-diameter crater on its rim.
Credit: ESA/DLR/FU Berlin (G. Neukum).