Editing Mira (section)

==Observation history==
[[File:Mira light curve.png|thumb|left|upright=1.2|Visual [[light curve]] of Mira, generated using the [[AAVSO]] light curve generator tool{{full citation needed|date=December 2021}}]]
Evidence that the variability of Mira was known in [[History of China|ancient China]], [[Babylon]] or [[Ancient Greece|Greece]] is at best only circumstantial.<ref name=wilk/> What is certain is that the variability of Mira was recorded by the astronomer [[David Fabricius]] beginning on August 3, 1596. Observing what he thought was the planet [[Mercury (planet)|Mercury]] (later identified as [[Jupiter]]), he needed a reference star for comparing positions and picked a previously unremarked third-magnitude star nearby. By August 21, however, it had increased in brightness by one [[Apparent magnitude|magnitude]], then by October had faded from view. Fabricius assumed it was a nova, but then saw it again on February 16, 1609.<ref name=hr/>

In 1638 [[Johannes Phocylides Holwarda|Johannes Holwarda]] determined a period of the star's reappearances, eleven months; he is often credited with the discovery of Mira's variability. [[Johannes Hevelius]] was observing it at the same time and named it Mira in 1662, for it acted like no other known star. [[Ismail Bouillaud]] then estimated its period at 333 days, less than one day off the modern value of 332 days. Bouillaud's measurement may not have been erroneous: Mira is known to vary slightly in period, and may even be slowly changing over time. The star is estimated to be a six-billion-year-old [[red giant]].<ref name=apj275/>

[[File:Mira the star.jpg|thumb|left|Mira as seen from the Earth]]
There is considerable speculation as to whether Mira had been observed prior to Fabricius. Certainly [[Algol]]'s history (known for certain as a variable only in 1667, but with legends and such dating back to antiquity showing that it had been observed with suspicion for millennia) suggests that Mira might have been known, too. [[Karl Manitius]], a modern translator of [[Hipparchus]]' ''Commentary on Aratus'', has suggested that certain lines from that second-century text may be about Mira. The other pre-telescopic Western catalogs of [[Ptolemy]], [[al-Sufi]], [[Ulugh Beg]] and [[Tycho Brahe]] turn up no mentions, even as a regular star. There are three observations from Chinese and Korean archives, in 1596, 1070 and the same year when Hipparchus would have made his observation (134 BC) that are suggestive.{{citation needed|date=October 2017}}

An estimate obtained in 1925 from interferometry by [[Francis G. Pease]] at the [[Mount Wilson Observatory]] gave Mira a diameter of 250-260 million miles (402 to 418 million km, or approximately {{Solar radius|290-300|link=y}}), making it the then-second largest star known and comparable to historical estimates of [[Betelgeuse]],<ref>{{Cite journal |last=Pease |first=F. G. |date=1925 |title=The Diameter of Mira Ceti at the 1925 Maximum |url=https://www.jstor.org/stable/40693379 |journal=Publications of the Astronomical Society of the Pacific |volume=37 |issue=216 |pages=89–90 |jstor=40693379 |issn=0004-6280}}</ref> surpassed only by [[Antares]].<ref>{{Cite journal |date=1925 |title=Science News |url=https://www.jstor.org/stable/1650052 |journal=Science |volume=61 |issue=1576 |pages=x–xiv |jstor=1650052 |issn=0036-8075}}</ref> On the contrary, [[Otto Struve]] thought of Mira as a [[red supergiant]] with an approximate radius of {{Solar radius|500}}, while modern consensus accepts Mira to be a highly evolved [[asymptotic giant branch]] star.<ref>{{Cite book |url=http://archive.org/details/Galaxy_v23n06_1965-08 |title=Galaxy v23n06 (1965 08)}}</ref>