A thick plume of smoke blew eastward across Montana, Wyoming, and the Dakotas on August 15, 2007. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying on NASA’s Terra satellite took this picture the same day. In this image, the smoke appears as a semi-transparent gray blur across the middle of the image. In contrast, clouds in the area are opaque and bright white. Red dots in the image indicate fires, but they are not responsible for the massive quantity of smoke in the region. The smoke results from fires farther west.