This radar image is 300 kilometers across. The plain is composed of many lava flows. The rough textured ''aa'' flows show up as dark in the image, and the smoother ''pahoehoe'' lava is bright to the radar. The very dark splotches are made by meteors that exploded in the thick atmosphere and rained down dust. Part of one of the meteors survived to leave a crater in the middle of the dark splotch.
Credit: NASA/JPL
