On Jan. 17, the Mexican government announced it was distributing food to particularly hard-hit indigenous Tarahumara communities in northern Mexico's Chihuahua state. This image shows vegetation growth between July and September, the heart of the growing season.
The image was made with data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA's Terra satellite, which measures both near infrared light and visible light. Healthy plants absorb visible light and reflect infrared light. By comparing the amount of visible and infrared light reflected from a region, scientists can estimate the density of healthy plants, a measurement called a vegetation index. In this case, the vegetation index from the 2011 growing season is compared with the average vegetation index observed between 2000 and 2010.
Areas in which plants grew more than average are green, and areas where plants grew less are brown. Drought clearly slowed plant growth in both the United States and Mexico. The drought is the worst in northern Mexico in 71 years, according to the Mexican government.