HOW DOES REMOTE SENSING WORK?
Remote sensing satellites collect image data either actively or passively. Radar satellites collect data actively by sending a known signal from the satellite to the earth and measuring the portion of the signal that is returned. A passive device measures the incoming energy, either started at the sun and reflected by the object, or started at the object as a result of its temperature. Every object reflects electromagnetic energy in various wavelengths determined by the object’s physical and chemical structure.
