Editing Planetary system (section)

===Speculation on extrasolar planetary systems===
In the 16th century the Italian philosopher [[Giordano Bruno]], an early supporter of the [[Nicolaus Copernicus|Copernican]] theory that Earth and other planets orbit the Sun, put forward the view that the fixed stars are similar to the Sun and are likewise accompanied by planets. He was burned at the stake for his ideas by the [[Roman Inquisition]].<ref>"Cosmos" in
 ''The New Encyclopædia Britannica'' (15th edition, Chicago, 1991) '''16''':787:2a. "For his advocacy of an infinity of suns and earths, he was burned at the stake in 1600."</ref>

In the 18th century, the same possibility was mentioned by [[Sir Isaac Newton]] in the "[[General Scholium]]" that concludes his ''[[Philosophiae Naturalis Principia Mathematica|Principia]]''. Making a comparison to the Sun's planets, he wrote "And if the fixed stars are the centres of similar systems, they will all be constructed according to a similar design and subject to the dominion of ''One''."<ref>
{{Cite book |last1      = Newton
 |first1     = Isaac
 |first2    = I. Bernard
 |last2     = Cohen
 |first3    = Anne
 |last3     = Whitman
 |title     = The Principia: A New Translation and Guide
 |publisher = University of California Press
 |date      = 1999
 |orig-year  = First published 1713
 |page      = 940
 |isbn      = 0-520-20217-1
 |url       = https://archive.org/details/keytonewtonsdyna0000brac
|url-access = registration
 }}
</ref>

His theories gained popularity through the 19th and 20th centuries despite a lack of supporting evidence. Long before their confirmation by astronomers, conjecture on the nature of planetary systems had been a focus of the [[search for extraterrestrial intelligence]] and [[Extrasolar planets in fiction|has been a prevalent theme in fiction]], particularly science fiction.