Hot spots across Southeastern Europe from 21 to 26 August 2007 have been detected with instruments aboard ESA satellites, which have been continuously surveying fires burning across the Earth’s surface for a decade. Working like thermometers in the sky, the Along Track Scanning Radiometer (ATSR) on ESA’s ERS-2 satellite and the Advanced Along Track Scanning Radiometer (AATSR) on ESA’s Envisat satellite measure thermal infrared radiation to take the temperature of Earth's land surfaces.