Earth observation (EO) is the gathering of information about planet Earth's physical, chemical and biological systems via remote sensing technologies supplemented by earth surveying techniques, encompassing the collection, analysis and presentation of data. Earth observation is used to monitor and assess the status of, and changes in, the natural environment and the built environment. In recent years, Earth observation has become technologically increasingly sophisticated. It has also become more important due to the dramatic impact that modern human civilization is having on the planet Earth, and the need to minimize negative impacts along with the opportunities Earth observation provides to improve social and economic well-being.
The term Earth observation is used in two ways, leading to confusion. In Europe, in particular, it has often been used to refer to satellite-based remote sensing, but the term is also used to refer to any form of observations of the Earth system, including in situ and airborne observations, for example. The Group on Earth Observations, which has over 100 member countries and over 100 participating organizations, uses EO in this broader sense. To add to the confusion, in the US, for example, the term remote sensing is often used to refer to satellite-based remote sensing, but sometimes used more broadly for observations using any form of remote sensing technology, including airborne sensors and even ground-based sensors such as cameras. Perhaps the least ambiguous term to use for satellite-based sensors is satellite remote sensing, or SRS, an acronym which is gradually starting to appear in the literature.
Earth observations can include:
Just as Earth observations consist of a wide variety of possible elements, they can be applied to a wide variety of possible uses. Some of the specific applications of Earth observations are:
The quality and quantity of Earth observations continue to mount rapidly. 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, near-real time observations.