Editing Satellite (section)

=== Earth observation ===
{{Main|Earth observation satellite}}
[[File:Earth Radiation Budget Satellite.jpg|thumb|Deployment of the [[Earth Radiation Budget Satellite]] on [[STS-41-G]], collecting data on Earth's weather and climate]]
Earth observation satellites are designed to monitor and survey the Earth, called [[remote sensing]]. Most Earth observation satellites are placed in low Earth orbit for a high data resolution, though some are placed in a [[geostationary orbit]] for an uninterrupted coverage. Some satellites are placed in a [[Sun-synchronous orbit]] to have consistent lighting and obtain a total view of the Earth. Depending on the satellites' functions, they might have a [[Satellite imagery|normal camera]], [[Space-based radar|radar]], [[lidar]], [[photometer]], or atmospheric instruments. Earth observation satellite's data is most used in [[archaeology]], [[cartography]], [[environmental monitoring]], [[meteorology]], and [[reconnaissance]] applications.{{Citation needed|date=July 2022}} As of 2021, there are over 950 Earth observation satellites, with the largest number of satellites operated with [[Planet Labs]].<ref>{{cite web |date=18 August 2021 |title=How many Earth observation satellites are orbiting the planet in 2021? |url=https://www.pixalytics.com/eo-sats-2021/ |last1=Andy |website=Pixalytics |url-status=live |archive-url=https://web.archive.org/web/20220721104450/https://www.pixalytics.com/eo-sats-2021/ |archive-date=21 July 2022 |access-date=25 May 2022}}</ref>

[[Weather satellite]]s monitor [[cloud]]s, [[Street light|city lights]], [[fire]]s, effects of [[pollution]], [[auroral light|aurora]]s, [[Dust storm|sand and dust storms]], [[snow]] cover, [[ice]] mapping, boundaries of [[ocean current]]s, [[energy]] flows, etc. Environmental monitoring satellites can detect changes in the Earth's [[vegetation]], atmospheric trace gas content, sea state, ocean color, and ice fields. By monitoring vegetation changes over time, droughts can be monitored by comparing the current vegetation state to its long term average.<ref>{{cite web |website=Earth Observatory |publisher=NASA |url=http://earthobservatory.nasa.gov/Drought/ |title=Drought and Vegetation Monitoring |archive-url=https://web.archive.org/web/20080819121047/http://earthobservatory.nasa.gov/Drought/ |archive-date=19 August 2008 |access-date=4 July 2008}} {{PD-notice}}</ref> Anthropogenic emissions can be monitored by evaluating data of tropospheric NO<sub>2</sub> and SO<sub>2</sub>.{{Citation needed|date=July 2022}}