Editing Radio astronomy (section)

==Astronomical sources==
{{Main|Astronomical radio source}} {{See also|Radio object with continuous optical spectrum}}
[[File:GCRT J1745-3009 2.jpg|thumb|A radio image of the central region of the Milky Way galaxy. The arrow indicates a supernova remnant which is the location of a newly discovered transient, bursting low-frequency radio source [[GCRT J1745-3009]].]]
Radio astronomy has led to substantial increases in astronomical knowledge, particularly with the discovery of several classes of new objects, including [[pulsar]]s, [[quasar]]s<ref name=Shields>{{cite journal|last1=Shields|first1=Gregory A.|title=A brief history of AGN|journal=The Publications of the Astronomical Society of the Pacific|date=1999|volume=111|issue=760|pages=661–678|access-date=3 October 2014|url=http://ned.ipac.caltech.edu/level5/Sept04/Shields/Shields3.html|doi=10.1086/316378|arxiv=astro-ph/9903401|bibcode=1999PASP..111..661S|s2cid=18953602|archive-date=12 September 2009|archive-url=https://web.archive.org/web/20090912025415/http://nedwww.ipac.caltech.edu/level5/Sept04/Shields/Shields3.html|url-status=live}}</ref> and [[radio galaxy|radio galaxies]]. This is because radio astronomy allows us to see things that are not detectable in optical astronomy. Such objects represent some of the most extreme and energetic physical processes in the universe.

The [[cosmic microwave background radiation]] was also first detected using radio telescopes. However, radio telescopes have also been used to investigate objects much closer to home, including observations of the [[Sun]] and solar activity, and radar mapping of the [[Solar System|planets]].

Other sources include:
* [[Sun]]
* [[Jupiter]]
* [[Sagittarius A]], the [[Galactic Center]] of the [[Milky Way]], with one portion [[Sagittarius A*]] thought to be a radio wave–emitting [[supermassive black hole]]
* [[Active galactic nucleus|Active galactic nuclei]] and [[pulsar]]s have jets of charged particles which emit [[synchrotron radiation]]
* Merging [[galaxy cluster]]s often show diffuse radio emission<ref>{{cite web |url=http://www.arcetri.astro.it/~buttery/thesis/node69.html |title=Conclusion |access-date=2006-03-29 |url-status=dead |archive-url=https://web.archive.org/web/20060128231925/http://www.arcetri.astro.it/~buttery/thesis/node69.html |archive-date=2006-01-28 }}</ref>
* [[Supernova remnant]]s can also show diffuse radio emission; [[pulsar]]s are a type of supernova remnant that shows highly synchronous emission.
* The [[cosmic microwave background]] is [[blackbody]] radio/microwave emission

Earth's radio signal is mostly natural and stronger than for example Jupiter's but is produced by Earth's [[aurora]]s and bounces at the [[ionosphere]] back into space.<ref name="Geophysical Institute 1983 r818">{{cite web | title=The Earth is a Strong Radio Source even without Man's Tinkering | website=Geophysical Institute | date=June 23, 1983 | url=https://www.gi.alaska.edu/alaska-science-forum/earth-strong-radio-source-even-without-mans-tinkering | access-date=May 2, 2024}}</ref>