Remote sensing is described as the science of getting information about an object or an area through a satellite or an aircraft from a distance. It works on the basis of the collection of data, detected by the energy reflected from the earth. The energy is detected through the sensors mounted on an aircraft or any satellite.
The remote sensors can be active or passive. The active sensors collect data about the earth through internal stimuli. It is the laser beam remote sensing system that sends a laser onto the surface of the earth and measures the time taken by the laser to reflect back to a sensor.
On the other hand, the passive remote sensors collect data through external stimuli. They detect the natural energy emitted or reflected from the earth’s surface. The most common source of radiation is the sunlight which is detected by the passive sensors.
Remote sensing is acquiring information without physical contact.