Editing History of astronomy (section)

===Stellar astronomy===
[[Cosmic pluralism]] is the name given to the idea that the stars are distant suns, perhaps with their own planetary systems.
Ideas in this direction were expressed in antiquity, by [[Anaxagoras]] and  by [[Aristarchus of Samos]], but did not find mainstream acceptance. The first astronomer of the European Renaissance to suggest that the stars were distant suns was [[Giordano Bruno]] in his ''De l'infinito universo et mondi'' (1584). This idea, together with a belief in intelligent extraterrestrial life, was among the charges brought against him by the Inquisition.
The idea became mainstream in the later 17th century, especially following the publication of ''[[Conversations on the Plurality of Worlds]]'' by [[Bernard Le Bovier de Fontenelle]] (1686), and by the early 18th century it was the default working assumptions in stellar astronomy.

The Italian astronomer [[Geminiano Montanari]] recorded observing variations in luminosity of the star [[Algol]] in 1667. Edmond Halley published the first measurements of the [[proper motion]] of a pair of nearby "fixed" stars, demonstrating that they had changed positions since the time of the ancient [[Ancient Greece|Greek]] astronomers Ptolemy and Hipparchus. [[William Herschel]] was the first astronomer to attempt to determine the distribution of stars in the sky. During the 1780s, he established a series of gauges in 600 directions and counted the stars observed along each line of sight. From this he deduced that the number of stars steadily increased toward one side of the sky, in the direction of the Milky Way [[Galactic Center|core]]. His son [[John Herschel]] repeated this study in the southern hemisphere and found a corresponding increase in the same direction.<ref>{{cite journal
 | last=Proctor | first=Richard A.
 | title=Are any of the nebulæ star-systems? | journal=Nature
 | date=1870 | pages=331–333
 | url=http://digicoll.library.wisc.edu/cgi-bin/HistSciTech/HistSciTech-idx?type=div&did=HISTSCITECH.0012.0052.0005&isize=M
 | issue=13
 | doi=10.1038/001331a0 | volume=1 |bibcode= 1870Natur...1..331P| doi-access=free}}</ref> In addition to his other accomplishments, William Herschel is noted for his discovery that some stars do not merely lie along the same line of sight, but are physical companions that form binary star systems.<ref name="Magill1992">{{cite book|author=Frank Northen Magill|title=Magill's Survey of Science: A-Cherenkov detectors|url=https://books.google.com/books?id=W33WAAAAMAAJ|year=1992|publisher=Salem Press|isbn=978-0-89356-619-7|page=219}}</ref>