REMOTE SENSING
In the broadest sense, remote sensing is the measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. In practice, remote sensing is the utilization at a distance (as from aircraft, spacecraft, satellite, or ship) of any device for gathering information about the environment. Thus an aircraft taking photographs, Earth observation and Weather satellites, monitoring of a fetus in the womb via ultrasound, and space probes are all examples of remote sensing. In modern usage, the term generally refers to techniques involving the use of instruments aboard aircraft and spacecraft rather than other fields which are considered to be under medical imaging or photogrammetry.
While all astronomy could be considered remote sensing (in fact, extremely remote sensing) the term “remote sensing” is normally only applied to terrestrial observations.