A View Looking Down on the North Pole of Mercury (Center)
Red circles show the locations of impact craters larger than 20 km in diameter. The area of contiguous northern high-latitude smooth plains mapped by MESSENGER from orbit (inside the black line) covers 4.7 million square kilometers, over 6% of the surface of Mercury. Note that the number of craters superposed on the plains is much less than in the surrounding areas, indicating the relative youth of the plains.
Credit: Courtesy of Science/AAAS and Brown University