Mercury's Vast Expanses of Smooth Plains

This scene, a mosaic of images acquired as MESSENGER approached Mercury for its third flyby of the planet, shows a large expanse of smooth plains near the center of the image. Most smooth plains are believed to have formed by lavas that flooded Mercury's surface. In this view, craters are visible that have been nearly filled with lava, leaving only traces of their circular rims. Curving scarps (cliffs) and "wrinkle ridges" can also be seen running mostly from top to bottom in the image. The density of impact craters on the smooth plains is less than on the heavily cratered terrain visible in the upper right and lower right corners of this image. The presence of fewer impact craters per unit area means that the volcanic smooth plains are younger than the battered cratered terrain. During orbital observations beginning in 2011, MESSENGER will gather high-resolution and color imaging data to map the global extent of Mercury's volcanic smooth plains, gaining clues to the composition of the plains and unraveling the history of volcanism on the Solar System's innermost planet.

Source: Courtesy NASA/JPL-Caltech.

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