Galle Crater (Natural Colors; credits: NASA/MGS/MSSS)

Caption NASA originale:"The 2 pictures shown here are taken from the same daily global image mosaic (the only difference is that each was processed slightly differently). The pictures show Galle Crater, informally known as "Happy Face," as it appeared in early Southern Winter. The white-ish gray surfaces are coated with wintertime carbon dioxide frost. The pattern of frost distribution gives the appearance that "Happy Face" has opened its mouth. Galle Crater is located on the east rim of Argyre Planitia at 51°S, 31°W. Sunlight illuminates the scene from the upper left. Galle Crater is about 230 Km (143 mi) across".