编辑“︁Ο”︁（章节）

===天文学===
Omicron用于指定一个星座组中的第十五颗星，它的序数位置是星等和位置的不规则函数。<ref name="martin">
{{cite book
 |last=Martin |first=Martha Evans
 |year=1907
 |title=The Friendly Stars
 |edition=1st |page=[https://archive.org/details/friendlystars01martgoog/page/n154 135]
 |publisher=[[Harper (publisher)|Harper & Brothers Publishers]]
 |location=New York
 |url=https://archive.org/details/friendlystars01martgoog
 |access-date=8 February 2016
}}
</ref><ref name="wilk">{{cite book
 |last=Wilk
 |first=Stephen R.
 |year=2007
 |title=Medusa: Solving the Mystery of the Gorgon
 |edition=1st
 |page=201
 |publisher=[[牛津大學出版社|Oxford University Press]]
 |location=New York, NY; London, UK
 |isbn=9780199887736
 |url=https://books.google.com/books?id=OnHO4orvz18C&pg=PT201
 |access-date=8 February 2016
 |archive-date=2022-01-30
 |archive-url=https://web.archive.org/web/20220130234442/https://books.google.com/books?id=OnHO4orvz18C&pg=PT201
 |dead-url=no
 }}</ref>这样的恒星包括[[车府增十六|Omicron Andromedae]]、[[蒭藁增二|Omicron Ceti]]和[[英仙座ο|Omicron Persei]]。

在[[克劳狄乌斯·托勒密]]（约{{circa|100–170}}）的《[[天文學大成]]》中，1 ... 59的[[六十進制]]数字表是以希腊数字的传统方式{{efn
|name=why_omicron_is_available| 
[[Sexagesimal]] [[希腊数字|Greek numbers]] in the ''[[天文學大成|Almagest]]'' are [[希腊数字|conventional]]: &nbsp; 1 2 3 4 5 6 7 8 9  {{math|&nbsp;{{=}}&nbsp; &prime;α  &prime;β  &prime;γ  &prime;&delta;  &prime;&epsilon;    &prime;''ϝ''  &prime;&zeta;  &prime;&eta;  &prime;θ}}&nbsp;. Notice that ancient [[digamma]] ({{mvar|ϝ}}) is used for &nbsp;6&nbsp; instead of [[zeta]] ({{math|&zeta;}}, which is used for 7)&nbsp;; &nbsp; 10  20  30  40  50 {{math|&nbsp;{{=}}&nbsp; &prime;&iota;  &prime;&kappa;  &prime;λ  &prime;&mu;  &prime;&nu;}}&nbsp;. Adjacent number-letters add, so all the other numbers are made by letter pairs, such as &nbsp;29  30  31 {{math| &nbsp;{{=}}&nbsp; &prime;&kappa;θ  &prime;λ  &prime;λα}}&nbsp;. The number 59 ({{math|&prime;&nu;θ}}) is the largest value used in a single cell in [[六十進制|sexagesimal]]. That leaves [[Ξ|xi]] ({{math|&xi;}}) and the letters following  it &nbsp;{{math| &xi; &omicron; &pi; ϙ &rho; &sigma; &tau; &upsilon; &phi; &chi; &psi; &omega; ϡ}}&nbsp; free for other use: [[克劳狄乌斯·托勒密|Ptolemy]] picked {{math|&nbsp;&omicron;&nbsp;}}, which normally was used for 70, to mark empty (zero) cells, perhaps because the word for "nothing", {{math|οὐδέν}} starts with an omicron.
}}表示：{{math|&prime;α}} ... {{math|&prime;&nu;θ}}。由于字母omicron[在标准系统中代表70（′ο）]在六进制中没有使用，它被重新用于代表一个空的数字单元。在某些版本中，该单元格只是留有空白（那里没有东西=数值为零），但为了避免复制错误，人们倾向于用omicron标记一个零单元格，就像现代表格中的空白单元格用破折号（-）填充一样。Omicron和破折号都意味着“这不是一个错误，这个单元格实际上应该是空的”。巧合的是，古代的零值omicron（{{math|&omicron;}}）类似于现代[[阿拉伯数字]]的零（0）。