A method for detecting a hot target on the Earth by a satellite is disclosed. The satellite includes a sensor for acquiring data in spectral channels in the IR spectrum, and a navigation system for detecting position and orientation data of the satellite. The method includes the steps of subjecting the acquired data to a system correction by radiometric and geometric calibration files stored on the satellite; detecting a hot target on board from the system-corrected data by multi-channel thresholding; geo-referencing the hot target by the position and orientation data of the satellite and the geometric calibration files; temporarily storing the geo-referenced hot target on the satellite; and transmitting the temporarily stored hot target by a transmitting unit to a receiving unit on the Earth.