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Outer space is certainly spacious, but it is far from empty.  Outer space is sparsely filled with several dozen types of [[organic chemistry|organic]] [[molecule]]s discovered to date by [[rotational spectroscopy|microwave spectroscopy]],  [[cosmic microwave background radiation|blackbody radiation]] left over from the [[big bang]] and the origin of the universe, and [[cosmic ray]]s, which include [[ion]]ized [[atomic nucleus|atomic nuclei]] and various [[subatomic particle]]s. There is also some gas, [[Plasma (physics)|plasma]] and [[dust]], and small [[meteor]]s.  Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to spacecraft. Some of this [[space debris|debris]] re-enters the atmosphere periodically.

Outer space is certainly spacious, but it is far from empty.  Outer space is sparsely filled with several dozen types of [[organic chemistry|organic]] [[molecule]]s discovered to date by [[rotational spectroscopy|microwave spectroscopy]],  [[cosmic microwave background radiation|blackbody radiation]] left over from the [[big bang]] and the origin of the universe, and [[cosmic ray]]s, which include [[ion]]ized [[atomic nucleus|atomic nuclei]] and various [[subatomic particle]]s. There is also some gas, [[Plasma (physics)|plasma]] and [[dust]], and small [[meteor]]s.  Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to spacecraft. Some of this [[space debris|debris]] re-enters the atmosphere periodically.

Although the planet Earth is currently the only known body within the solar system to support life, current evidence suggests that in the distant past the planet [[Mars]] possessed bodies of liquid water on the surface.<ref>{{cite journal | author = Bibring J, Langevin Y, Mustard J, Poulet F, Arvidson R, Gendrin A, Gondet B, Mangold N, Pinet P, Forget F, Berthé M, Bibring J, Gendrin A, Gomez C, Gondet B, Jouglet D, Poulet F, Soufflot A, Vincendon M, Combes M, Drossart P, Encrenaz T, Fouchet T, Merchiorri R, Belluci G, Altieri F, Formisano V, Capaccioni F, Cerroni P, Coradini A, Fonti S, Korablev O, Kottsov V, Ignatiev N, Moroz V, Titov D, Zasova L, Loiseau D, Mangold N, Pinet P, Douté S, Schmitt B, Sotin C, Hauber E, Hoffmann H, Jaumann R, Keller U, Arvidson R, Mustard J, Duxbury T, Forget F, Neukum G | title = Global mineralogical and aqueous mars history derived from OMEGA/Mars Express data | journal = Science | volume = 312 | issue = 5772 | pages = 400-4 | year = 2006 | id = PMID 16627738}}</ref> For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen.

Although the planet Earth is currently the only known body within the solar system to support life, current evidence suggests that in the distant past the planet [[Mars]] possessed bodies of liquid water on the surface. For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen. If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist.[http://www.msnbc.msn.com/id/7129347/]

If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist.<ref>{{cite web | first = Tariq | last = Malik | date = 2005-03-08 | url = http://www.msnbc.msn.com/id/7129347/ | title = Hunt for Mars life should go underground | publisher = The Brown University News Bureau | language = English |accessmonthday=September 4|accessyear=2006}}</ref>

Conditions on the other terrestrial planets, [[Mercury (planet)|Mercury]] and [[Venus]], appears to be too harsh to support life as we know it. But it has been conjectured that [[Europa (moon)|Europa]], the fourth-largest moon of [[Jupiter]], may possess a sub-surface ocean of liquid water and could potentially host life.<ref>{{cite web | author = Scott Turner | date = 1998-03-02 | url = http://www2.jpl.nasa.gov/galileo/news8.html | title = Detailed Images From Europa Point To Slush Below Surface | publisher = The Brown University News Bureau | language = English |accessmonthday=September 28|accessyear=2006}}</ref>

Conditions on the other terrestrial planets, [[Mercury (planet)|Mercury]] and [[Venus]], appears to be too harsh to support life as we know it. But it has been conjectured that [[Europa (moon)|Europa]], the fourth-largest moon of [[Jupiter]], may possess a sub-surface ocean of liquid water and could potentially host life.[http://www2.jpl.nasa.gov/galileo/news8.html]

Recently, the team of [[Stéphane Udry]] have discovered a new planet named [[Gliese 581 c]], which is an [[extrasolar]] planet orbiting the [[red dwarf]] [[star]] [[Gliese 581]]. Gliese 581 c appears to lay in the [[habitable zone]] of space surrounding the [[star]], and therefore could possibly host [[life]] as we know it.

Recently, the team of [[Stéphane Udry]] have discovered a new planet named [[Gliese 581 c]], which is an [[extrasolar]] planet orbiting the [[red dwarf]] [[star]] [[Gliese 581]]. Gliese 581 c appears to lay in the [[habitable zone]] of space surrounding the [[star]], and therefore could possibly host [[life]] as we know it.

== See also ==

== See also ==