remote sensing is the science of obtaining information about earth features from measurements made at a distance. remotely sensed data comes in many forms, such as satellite imagery, aerial photography, and data obtained from hand-held sensors. geographers increasingly use remotely sensed data to obtain information about the earth's land surface, ocean, and atmosphere, because it: (a) supplies objective information at a variety of spatial scales (local to global), (b) provides a synoptic view of the area of interest, (c) allows access to distant and inaccessible sites, (d) provides spectral information outside the visible portion of the electromagnetic spectrum, and (e) facilitates studies of how features/areas change over time. remotely sensed data may be analysed either independently of, or in conjunction with other digital data layers (e.g., in a geographic information system).