[5] Earth observation is used to monitor and assess the status of and changes in natural and built environments.
The GEO, which has over 100 member countries and over 100 participating organizations, uses EO in this broader sense.
[6] Perhaps the least ambiguous term to use for satellite-based sensors is satellite remote sensing (SRS), an acronym which is gradually starting to appear in the literature.
In addition to the ongoing launch of new remote-sensing satellites, increasingly sophisticated in situ instruments located on the ground, on balloons and airplanes, and in rivers, lakes and oceans, are generating increasingly comprehensive, nearly real-time observations.
It has also become more important due to the dramatic impact that modern human civilization is having on the world and the need to minimize negative effects (e.g. geohazards),[9] along with the opportunities such observation provides to improve social and economic well-being.