Space

[[File:Flammarion_with_caption.jpg|thumb|right|It doesn't look like this…]]
{{Astronomy}}
{{cquote|Space: the final frontier…|||The intro to ''[[Star Trek]]''<ref>{{wpa|Where no man has gone before}}</ref>}}
'''Space''' is big. Really big.<ref>[http://www.amnh.org/our-research/hayden-planetarium/digital-universe Seriously, it's huge.]</ref> You just won't believe how vastly hugely mind-bogglingly big it is. You may think it's a long way down the road to the [[Chemistry|chemist]], but that's just peanuts to space.<ref group=note>With thanks to [[Douglas Adams]]. See also this [[BBC]] Infographic attempting to convey distance just within the Solar System: [http://www.bbc.co.uk/bbc.com/future/bespoke/space_infographic.html How Big Is Our Own Solar System?]</ref>

==The Universe==
{{main|Universe}}
On the most basic level, "space" can be summed up as the X, Y, and Z (forward/backward, up/down, left/right) coordinates that make up the Universe. Space, generally, is every''where'' that every''thing'' exists in. In mathematical constructs and physical [[theories]], space is melded together with [[time]] to make a four-dimensional [[spacetime]]. So where X, Y, and Z are our physical dimensions, A to B represents the ''when'' we are inside of X, Y, and Z.

==Outer space==
"Space" is also used to refer to "outer space", or "up there as opposed to down here". There is no definite boundary where outer space begins, but it is generally said to begin about {{wpl|Kármán line|80-100 kilometers}} above the surface of the [[Earth]]. This is just above the level of the mesopause (the top of the mesosphere) where temperatures are as low as −100° C and the atmospheric pressure is 0.2% of that at sea level, or less. The official [[U.S.]] definition of an astronaut is someone who has flown above this level.

Most of outer space is a near vacuum — that is, there are very few [[atoms]] or [[molecule]]s floating around it (as little as one atom per cubic centimetre, which seems like a lot until you remember how small atoms are). It is mostly populated, apparently, by [[dark matter]], but contains a lot of dust and fine particles as well as objects that are large enough to be of concern: galaxies, [[star]]s, [[planet]]s, [[asteroid]]s, and so on.

==Space exploration==
"Space exploration" refers to the efforts of [[humanity]] to explore outer space. A lot of it is outside the scope of [[RationalWiki:Mission|RationalWiki's mission]], but more than a half-century of space exploration has given birth to some [[pseudohistory]] and many, many [[conspiracy theories]] — from the [[Moon landing hoax]] accusations to the [[Face on Mars]] and beyond. Then there is the belief that private firms will now assume responsibility for opening the space frontier.<ref>http://www.thespacereview.com/article/2321/1</ref> That the [[state]] normally opens physical and technological frontiers is an argument made by both John Hickman<ref>''Reopening the Space Frontier''. 2010. Common Ground. ISBN 978-1863358002.</ref> and [[Neil deGrasse Tyson]].<ref>''Space Chronicles: Facing the Ultimate Frontier''. 2012. W. W. Norton & Company. ISBN 978-0393082104.</ref>

==See also==
*[[Astronomy]]
*[[Cosmology]]
*[[NASA]]

==Notes==
{{reflist|group=note}}

==References==
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[[Category:Science]]
[[Category:Physics]]
[[Category:Astronomy]]
[[Category:Cosmology]]

Categories: Science, Physics, Astronomy, Cosmology