Editing Universe (section)

===Deep space astronomy===
During the 18th century, [[Immanuel Kant]] speculated that [[nebula]]e could be entire galaxies separate from the Milky Way,<ref name="m756" /> and in 1850, [[Alexander von Humboldt]] called these separate galaxies ''Weltinseln'', or "world islands", a term that later developed into "island universes".<ref>{{Cite journal |last=Jones |first=Kenneth Glyn |date=February 1971 |title=The Observational Basis for Kant's Cosmogony: A Critical Analysis |url=http://journals.sagepub.com/doi/10.1177/002182867100200104 |journal=Journal for the History of Astronomy |language=en |volume=2 |issue=1 |pages=29–34 |doi=10.1177/002182867100200104 |bibcode=1971JHA.....2...29J |s2cid=126269712 |issn=0021-8286 |access-date=February 27, 2023 |archive-date=February 27, 2023 |archive-url=https://web.archive.org/web/20230227183635/https://journals.sagepub.com/doi/10.1177/002182867100200104 |url-status=live }}</ref><ref>{{Cite journal |last=Smith |first=Robert W. |date=February 2008 |title=Beyond the Galaxy: The Development of Extragalactic Astronomy 1885–1965, Part 1 |url=http://journals.sagepub.com/doi/10.1177/002182860803900106 |journal=Journal for the History of Astronomy |language=en |volume=39 |issue=1 |pages=91–119 |doi=10.1177/002182860803900106 |bibcode=2008JHA....39...91S |s2cid=117430789 |issn=0021-8286 |access-date=February 27, 2023 |archive-date=February 27, 2023 |archive-url=https://web.archive.org/web/20230227183635/https://journals.sagepub.com/doi/10.1177/002182860803900106 |url-status=live }}</ref> In 1919, when the [[Hooker Telescope]] was completed, the prevailing view was that the universe consisted entirely of the Milky Way Galaxy. Using the Hooker Telescope, [[Edwin Hubble]] identified [[Cepheid variable]]s in several spiral nebulae and in 1922–1923 proved conclusively that [[Andromeda Galaxy|Andromeda Nebula]] and [[Triangulum Nebula|Triangulum]] among others, were entire galaxies outside our own, thus proving that the universe consists of a multitude of galaxies.<ref name="SharovNovikov1993">{{cite book|last1=Sharov|first1=Aleksandr Sergeevich|last2=Novikov|first2=Igor Dmitrievich|title=Edwin Hubble, the discoverer of the big bang universe|url=https://books.google.com/books?id=ttEwkEdPc70C&pg=PA34|access-date=December 31, 2011|date=1993|publisher=Cambridge University Press|isbn=978-0-521-41617-7|page=34|archive-date=June 23, 2013|archive-url=https://web.archive.org/web/20130623075250/http://books.google.com/books?id=ttEwkEdPc70C&pg=PA34|url-status=live}}</ref> With this Hubble formulated the [[Hubble constant]], which allowed for the first time a calculation of the age of the Universe and size of the Observable Universe, which became increasingly precise with better meassurements, starting at 2 billion years and 280 million light-years, until 2006 when data of the [[Hubble Space Telescope]] allowed a very accurate calculation of the age of the Universe and size of the Observable Universe.<ref name="p537">{{cite web | title=Cosmic Times | website=Imagine the Universe! | date=December 8, 2017 | url=https://imagine.gsfc.nasa.gov/educators/programs/cosmictimes/educators/guide/age_size.html | access-date=October 31, 2024}}</ref>

The modern era of [[physical cosmology]] began in 1917, when [[Albert Einstein]] first applied his [[general theory of relativity]] to model the structure and dynamics of the universe.<ref name="einstein_1917">{{cite journal |last=Einstein |first=Albert |author-link=Albert Einstein |date=1917 |title=Kosmologische Betrachtungen zur allgemeinen Relativitätstheorie |journal=Preussische Akademie der Wissenschaften, Sitzungsberichte |series=1917 |volume=(part 1) |pages=142–152}}</ref> The discoveries of this era, and the questions that remain unanswered, are outlined in the sections above.

{{wide image|Observable Universe Logarithmic Map (horizontal layout english annotations).png|2250px|Map of the observable universe with some of the notable astronomical objects known as of 2018. The scale of length increases exponentially toward the right. Celestial bodies are shown enlarged in size to be able to understand their shapes.}}
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 | header            = Location of the Earth in the universe
 | image1            = The Earth seen from Apollo 17.jpg
 | width1            = 82
 | caption1          = [[Earth]]
 | image2            = Solar System true color.jpg
 | width2            = 146
 | caption2          = [[Solar&nbsp;System]]
 | image3            = RadcliffeWave1.png
 | width3            = 146
 | caption3          = [[Radcliffe Wave]]
 | image4            = Milky Way Arms ssc2008-10.svg
 | width4            = 93
 | caption4          = [[Orion Arm]]
 | image5            = Artist's impression of the Milky Way (updated - annotated).jpg
 | width5            = 83
 | caption5          = [[Milky&nbsp;Way]]
 | image6            = Local Group and nearest galaxies.jpg
 | width6            = 111
 | caption6          = [[Local Group|Local&nbsp;Group]]
 | image7            = Local supercluster-ly.jpg
 | width7            = 86
 | caption7          = [[Virgo Supercluster|Virgo SCl]]
 | image8            = Observable universe r2.jpg
 | width8            = 83
 | caption8          = [[Laniakea Supercluster|Laniakea SCl]]
 | image9            = Observable Universe with Measurements 01.png
 | width9            = 83
 | caption9          = [[Observable universe]]
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}}