The Great Lakes dominate this true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image. Lake Superior covers the upper left corner. Beneath it is Lake Michigan, and to the right is Lake Huron. Under Lake Huron is Lake Erie (left) and Lake Ontario (right). The pale blue swirls in Lake Michigan are probably caused by a phytoplankton bloom or calcium carbonate (chalk) from the lake's limestone floor. Concrete-grey patches mark the locations of several cities throughout the Great Lakes region. Red dots indicate active fire locations.