These images show a composite of the best annual Landsat satellite imagery (USGS/NASA) from 1999 to 2012. The annual composites were generated by Google in the Google Earth Engine. The Landsat composites display “Top-of-Atmosphere,” or the most cloud-free, images at 30-meter resolution. More information on Landsat imagery is available from the Landsat website.
Google Maps/Google Earth. "Landsat Composites." Accessed through Resource Watch, (date). www.resourcewatch.org.