The distinction between the platforms and sensors. Propagates in accordance with wave theory. Has both magnetic and electrical properties.
Examples are visible light, heat, UV, x-rays.
Moves at the speed of light. Amplitude - height of the wave peak. The ultimate source of energy is the sun. Given these principles, we know something about how energy is made available for remote sensing. The atmosphere affects the spectral composition and the intensity of radiation sensed by all remote sensor devices.