Editing Variable star (section)

==Discovery==
An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star,
the eclipsing binary [[Algol]].<ref>{{cite journal|display-authors=6|author=Porceddu, S.|author2=Jetsu, L.|author3=Lyytinen, J.|author4=Kajatkari, P.|author5=Lehtinen, J.|author6=Markkanen, T.|author7=Toivari-Viitala, J.|title=Evidence of Periodicity in Ancient Egyptian Calendars of Lucky and Unlucky Days|journal = Cambridge Archaeological Journal|volume =18|issue=3|date = 2008|pages = 327–339|doi=10.1017/S0959774308000395|bibcode = 2008CArcJ..18..327P |s2cid=162969143|url=https://zenodo.org/record/896419 }}</ref><ref>{{cite journal|display-authors=6|author=Jetsu, L.|author2=Porceddu, S.|author3=Lyytinen, J.|author4=Kajatkari, P.|author5=Lehtinen, J.|author6=Markkanen, T.|author7=Toivari-Viitala, J.|title=Did the Ancient Egyptians Record the Period of the Eclipsing Binary Algol - The Raging One? |journal = The Astrophysical Journal|volume =773|issue=1|date = 2013|pages = A1 (14pp)|doi = 10.1088/0004-637X/773/1/1|arxiv = 1204.6206 |bibcode = 2013ApJ...773....1J |s2cid=119191453}}</ref><ref>{{cite journal|author=Jetsu, L.|author2=Porceddu, S.|title=Shifting Milestones of Natural Sciences: The Ancient Egyptian Discovery of Algol's Period Confirmed|journal = PLOS ONE|volume = 10 |issue=12|date = 2015|pages = e.0144140 (23pp)|doi=10.1371/journal.pone.0144140|pmid=26679699|pmc=4683080|arxiv = 1601.06990 |bibcode = 2015PLoSO..1044140J |doi-access=free}}</ref> [[Aboriginal Australians]] are also known to have observed the variability of [[Betelgeuse]] and [[Antares]], incorporating these brightness changes into narratives that are passed down through oral tradition.<ref>{{cite journal |last1=Hamacher |first1=D.W. |title=Observations of red-giant variable stars by Aboriginal Australians |journal=The Australian Journal of Anthropology |date=2018 |volume=29 |issue=1 |pages=89–107 |doi=10.1111/taja.12257 |arxiv=1709.04634 |bibcode=2018AuJAn..29...89H |hdl=11343/293572 |s2cid=119453488 |url=https://onlinelibrary.wiley.com/doi/full/10.1111/taja.12257|hdl-access=free }}</ref><ref>{{cite journal |last1=Schaefer |first1=B.E. |title=Yes, Aboriginal Australians can and did discover the variability of Betelgeuse |journal=Journal of Astronomical History and Heritage |date=2018 |volume=21 |issue=1 |pages=7–12 |doi=10.3724/SP.J.1440-2807.2018.01.02 |arxiv=1808.01862 |s2cid=119209432 |url=https://www.sciengine.com/JAHH/doi/10.3724/SP.J.1440-2807.2018.01.02}}</ref><ref>{{cite book |last1=Hamacher |first1=D.W. |title=The First Astronomers |date=2022 |publisher=Allen and Unwin |location=Sydney |isbn=9781760877200 |pages=144–166}}</ref>

Of the modern astronomers, the first variable star was identified in 1638 when [[Johannes Phocylides Holwarda|Johannes Holwarda]] noticed that [[Omicron Ceti]] (later named Mira) pulsated in a cycle taking 11 months; the star had previously been described as a nova by [[David Fabricius]] in 1596. This discovery, combined with [[supernova]]e observed in 1572 and 1604, proved that the starry sky was not eternally invariable as [[Aristotle]] and other ancient philosophers had taught. In this way, the discovery of variable stars contributed to the astronomical revolution of the sixteenth and early seventeenth centuries.

The second variable star to be described was the eclipsing variable Algol, by [[Geminiano Montanari]] in 1669; [[John Goodricke]] gave the correct explanation of its variability in 1784. [[Chi Cygni]] was identified in 1686 by [[Gottfried Kirch|G. Kirch]], then [[R Hydrae]] in 1704 by [[Giovanni Domenico Maraldi|G. D. Maraldi]]. By 1786, ten variable stars were known. John Goodricke himself discovered [[Delta Cephei]] and [[Beta Lyrae]]. Since 1850, the number of known variable stars has increased rapidly, especially after 1890 when it became possible to identify variable stars by means of photography.

In 1930, astrophysicist [[Cecilia Payne-Gaposchkin|Cecilia Payne]] published the book The Stars of High Luminosity,<ref>{{Cite book |last=Payne |first=Cecilia H. |url=http://archive.org/details/starsofhighlumin029206mbp |title=The Stars Of High Luminosity |date=1930 |publisher=McGraw Hill Book Company Inc. |others=Osmania University, Digital Library Of India}}</ref> in which she made numerous observations of variable stars, paying particular attention to [[Cepheid variable|Cepheid variables]].<ref>{{Cite web |title=Cecilia Payne-Gaposchkin {{!}} British Astronomer & Harvard Professor {{!}} Britannica |url=https://www.britannica.com/biography/Cecilia-Payne-Gaposchkin |access-date=2024-08-10 |website=www.britannica.com |language=en}}</ref> Her analyses and observations of variable stars, carried out with her husband, Sergei Gaposchkin, laid the basis for all subsequent work on the subject.<ref>{{Cite web |last=Turner |first=J |date=March 16, 2001 |title=Cecilia Helena Payne-Gaposchkin |url=http://cwp.library.ucla.edu/Phase2/Payne-Gaposchkin,_Cecilia_Helena@861234567.html |archive-url=https://web.archive.org/web/20121012003950/http://cwp.library.ucla.edu/Phase2/Payne-Gaposchkin,_Cecilia_Helena@861234567.html |archive-date=October 12, 2012 |website=Contributions of 20th Century Women to Physics}}</ref>

The latest edition of the [[General Catalogue of Variable Stars]]<ref>{{cite journal|bibcode=2001OAP....14..266S|title=General Catalogue of Variable Stars|journal=Odessa Astronomical Publications|volume=14|pages=266|last1=Samus|first1=N. N.|last2=Kazarovets|first2=E. V.|last3=Durlevich|first3=O. V.|year=2001}}</ref> (2008) lists more than 46,000 variable stars in the Milky Way, as well as 10,000 in other galaxies, and over 10,000 'suspected' variables.