Radio source 1146115 202940308 2008-04-03T01:07:48Z SmackBot 433328 Date the maintenance tags or general fixes {{Cleanup|date=April 2008}} '''Radio sources''' are objects in [[outer space]] that emit strong [[radio waves]]. Radio emission comes from hot [[gas]], [[electrons]] spiraling in [[magnetic field]]s and specific wavelengths emitted by [[atoms]] and [[molecules]] in space. In 1932, radio [[astronomer]], Karl Jansky detected [[radio waves]] coming from an unknown source in the centre of our [[galaxy]]. This was the first time that radio waves were detected from outer space.<ref>{{cite book|last=Koupelis|first=Theo|coauthors=Karl F. Kuhn|title=In Quest of the Universe|publisher=Jones & Bartlett Publishers|date=2007|edition=5th|pages=149|isbn=0763743879|url=http://books.google.com/books?id=WwKjznJ9Kq0C|accessdate=2008-04-02}}</ref> Other strong '''radio sources''' have been the remains of a [[supernova]] explosion in the Crab Nebula and [[pulsars]]. Short [[radio waves]] have come from complex [[molecules]] in dense clouds of [[gas]] where [[stars]] are giving birth. Searches have been taken to find out if there are other civilizations in our [[galaxy]] using [[radio waves]], but have had no successes. There are many sources of [[radio waves]] beyond our [[galaxy]], most of which are found in other galaxies. A few examples include [[neutral hydrogen]] and [[carbon monoxide]], mostly found in [[spiral galaxies]], and [[quasars]] (short for "quasi-stellar radio source"), which are point-like sources of radio waves. The radio frequencies of these two molecules were used to map a large portion of the Milky Way galaxy.<ref>{{cite book|last=Gonzalez|first=Guillermo|coauthors=ay Wesley Richards|title=The Privileged Planet|publisher=Regnery Publishing|date=2004|pages=382|isbn=0895260654|url=http://books.google.com/books?id=KFdu4CyQ1k0C|accessdate=2008-04-02}}</ref> Other kinds of [[electromagnetic radiation]] that are thought to be powered by [[supermassive black holes]] in the centers of [[elliptical galaxies]]. Scientists have also discovered weak [[background radiation]] left over from the [[Big Bang]] (the rapid expanion, roughly 13.7 billion years ago, that was the beginning of our [[universe]]). ==References== {{Reflist}} [[Category:Radio astronomy]] {{astronomy-stub}} {{physics-stub}} [[de:Radioquelle]] [[es:Radiofuente]] [[it:Radiosorgente]] [[pl:Radioźródło]] [[zh:無線電波源]]