Images: Satellites watch wildfires burn

A joint effort by a handful of agencies and a university has made it possible to track the progress of wildfires in the United States with maps updated several times a day and posted online for the public.

MODIS (Moderate Resolution Imaging Spectroradiometer) imaging devices mounted on two NASA satellites monitor the earth and can pinpoint a fire within a 500-meter distance.

The instruments return data that is then turned into maps such as this one, which shows the location of past and actively burning fires near the San Francisco Bay Area. On July 9, a wildfire broke out in Stanislaus County, Calif., east of San Jose, damaging parts of Henry Coe State Park.

Yellow on the map indicates an area that has burned at some point since Jan. 1; orange shows an actively burning area (in the last 24 hours); red shows an actively burning area (in the last 12 hours).

NASA, the U.S. Forest Service, the University of Maryland and the National Interagency Fire Center all participate in the program.