File:Western United States (MODIS 2017-10-29).jpg

English: As snow caps the peaks of the northern mountains in early autumn, 2017, the relentless summer fire season continues to scar forests across the western United States. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite acquired a true-color image of the scene on October 24.

Red hot spots are scattered across the region, appearing wherever vegetation grows in abundance, particularly in the forests of California, Oregon, Washington, and Idaho, as well as southwestern Canada. Each hot spot marks and area where the thermal bands on the MODIS instrument detected temperatures higher than background. When accompanied by smoke, as in this image, such hotspots are diagnostic for actively burning fire.

While it is possible to locate fires from space, the cause and type of fire isn’t so obvious. Most of the fires in California, Idaho, the Pacific Northwest and Canada are wildfires, ignited by accident, arson, or lightning strike. In contrast, many of the fires located in the mountains of Arizona have been ignited deliberately and managed to benefit croplands, grasslands, or forests. Most of these prescribed burns are designed to safely reduce the fuel load, thus reducing the risk of an out-of-control conflagration at a later time.