Remote sensing is the acquisition of information about an object or
phenomenon without making physical contact with the object, in contrast to in
situ or on-site observation. The term is applied especially to acquiring
information about Earth and other planets. Remote sensing is used in numerous
fields, including geophysics, geography, land surveying and most Earth science
disciplines (e.g. exploration geophysics, hydrology, ecology, meteorology,
oceanography, glaciology, geology). It also has military, intelligence,
commercial, economic, planning, and humanitarian applications, among others.
In current usage, the term remote sensing generally refers to the use of
satellite- or airborne-based sensor technologies to detect and classify
objects on Earth.