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{{Short description|Constellation straddling the celestial equator}}
{{About|the constellation}}
{{Use dmy dates|date=September 2021}}
{{Infobox constellation
| name = Cetus
| abbreviation = Cet
| genitive = Ceti
| pronounce = {{IPAc-en|ˈ|s|iː|t|ə|s}}, genitive {{IPAc-en|ˈ|s|iː|t|aɪ}}
| symbolism = the [[Whale]], [[Shark]], or [[Sea Monster]]
| RA = {{RA|00|26|22.2486}}–{{RA|03|23|47.1487}}<ref name=boundary>{{Cite journal | title=Cetus, constellation boundary | journal=The Constellations | publisher=[[International Astronomical Union]]|url=https://www.iau.org/public/themes/constellations/#cet | access-date=15 February 2014 }}</ref>
| dec= {{dec|10.5143948}}–{{dec|-24.8725095}}<ref name=boundary/>
| family = [[Perseus Family|Perseus]]
| areatotal = 1231
| arearank = 4th
| numbermainstars = 14
| numberbfstars = 88
| numberstarsplanets = 23
| numberbrightstars = 2
| numbernearbystars = 9
| brighteststarname = [[Beta Ceti|Diphda (β Cet)]]
| starmagnitude = 2.02
| neareststarname = [[Luyten 726-8]]
| stardistancely = 8.73
| stardistancepc = 2.68
| numbermessierobjects = 1
| meteorshowers = [[October Cetids]]<br />[[Eta Cetids]]<br />[[Omicron Cetids]]
| bordering = [[Aries (constellation)|Aries]]<br />[[Pisces (constellation)|Pisces]]<br />[[Aquarius (constellation)|Aquarius]]<br />[[Sculptor (constellation)|Sculptor]]<br />[[Fornax]]<br />[[Eridanus (constellation)|Eridanus]]<br />[[Taurus (constellation)|Taurus]]
| latmax = [[70th parallel north|70]]
| latmin = [[South Pole|90]]
| month = November
| notes = '''Note:''' †[[Mira]] (ο Cet) is magnitude 2.0 at its brightest.
}}

'''Cetus''' ({{IPAc-en|ˈ|s|iː|t|ə|s}}) is a [[constellation]], sometimes called 'the [[whale]]' in English. The [[Cetus (mythology)|Cetus]] was a [[sea monster]] in [[Greek mythology]] which both [[Perseus]] and [[Heracles]] needed to slay. Cetus is in the region of the sky that contains other water-related constellations: [[Aquarius (constellation)|Aquarius]], [[Pisces (constellation)|Pisces]] and [[Eridanus (constellation)|Eridanus]].

==Features==
[[Image:CetusCC.jpg|thumb|Cetus annotated with lines (a "stick figure") from a latitude further north (north of its declination), above a horizon, in conditions ideal for observation.]]

===Ecliptic===
Cetus is not among the 12 true [[zodiac]] constellations in the [[Epoch (astronomy)|J2000 epoch]], nor classical 12-part zodiac. The [[ecliptic]] passes less than 0.25° from one of its corners. Thus the Moon and planets will enter Cetus (occulting any stars as a foreground object) in 50% of their successive orbits briefly, and the southern part of the Sun appears in Cetus for about 14 hours each year on March 27 to 28. Many asteroids in belts have longer phases occulting the north-western part of Cetus, those with a slightly greater [[inclination]] to the ecliptic than the Moon and planets.

[[Astronomy on Mars#Celestial poles and ecliptic|As seen from Mars]], the ecliptic (apparent plane of the Sun and also the average plane of the planets which is almost the same) passes into it.

===Stars===
{{Main|List of stars in Cetus}}
[[Mira]] ("wonderful", [[Bayer designation|named by Bayer]]: [[Omicron Ceti]], a star of the neck of the asterism) was the first [[variable star]] to be discovered and the prototype of [[Mira variable|its class, Mira variables]]. Over a period of 332 days, it reaches a maximum [[apparent magnitude]] of 3 - visible to the naked eye - and dips to a minimum magnitude of 10, invisible to the unaided eye. Its seeming appearance and disappearance gave it its name. Mira [[pulsating variable|pulsates]] with a minimum size of 400 solar diameters and a maximum size of 500 solar diameters. 420 light-years from Earth, it was discovered by [[David Fabricius]] in 1596.{{sfn|Ridpath|Tirion|2001|pp=114-116}}

[[Alpha Ceti|α Ceti]], traditionally called Menkar ("the nose"), is a red-hued giant star of magnitude 2.5, 220 light-years from Earth. It is a wide [[double star]]; the secondary is [[93 Ceti]], a blue-white hued star of magnitude 5.6, 440 light-years away. [[Beta Ceti|β Ceti]], also called Deneb Kaitos and Diphda is the brightest star in Cetus. It is an orange-hued giant star of magnitude 2.0, 96 light-years from Earth. The traditional name "Deneb Kaitos" means "the whale's tail". [[Gamma Ceti|γ Ceti]], Kaffaljidhma ("head of the whale") is a very close double star. The primary is a blue-hued star of magnitude 3.5, 82 light-years from Earth, and the secondary is an F-type star of magnitude 6.6.{{sfn|Ridpath|Tirion|2001|pp=114-116}} [[Tau Ceti]] is noted for being a near [[Sun-like star]] at a distance of 11.9 light-years. It is a yellow-hued [[main-sequence star]] of magnitude 3.5.

[[AA Ceti]] is a triple [[star system]]; the brightest member has a magnitude of 6.2. The primary and secondary are separated by 8.4 arcseconds at an angle of 304 degrees. The tertiary is not visible in telescopes. AA Ceti is an eclipsing variable star; the tertiary star passes in front of the primary and causes the system's apparent magnitude to decrease by 0.5 magnitudes.{{sfn|Levy|2005|p=67}} [[UV Ceti]] is an unusual binary variable star. At 8.7 light-years from Earth, the system consists of two [[red dwarfs]]. Both of magnitude 13. One of the stars is a [[flare star]], which are prone to sudden, random outbursts that last several minutes; these increase the pair's apparent brightness significantly - as high as magnitude 7.{{sfn|Ridpath|Tirion|2001|pp=114-116}}

===Deep-sky objects===
[[File:Messier 77 spiral galaxy by HST.jpg|thumb|Messier 77 spiral galaxy - HST (Hubble Space Telescope).<ref>{{cite news|title=Hubble observes the hidden depths of Messier 77|url=http://www.spacetelescope.org/news/heic1305/|access-date=4 April 2013|newspaper=ESA/Hubble}}</ref>]]
[[File:Himmelsglob, 1602 - Skoklosters slott - 102439.tif|thumb|Cetus by Willem Blaeu, 1602.]]
Cetus lies far from the [[galactic plane]], so that many distant [[galaxy|galaxies]] are visible, unobscured by dust from the [[Milky Way]]. Of these, the brightest is [[Messier 77]] (NGC 1068), a 9th magnitude [[spiral galaxy]] near [[Delta Ceti]]. It appears face-on and has a clearly visible nucleus of magnitude 10. About 50 million light-years from Earth, M77 is also a [[Seyfert galaxy]] and thus a bright object in the [[radio spectrum]].{{sfn|Ridpath|Tirion|2001|pp=114-116}} Recently, the galactic cluster [[JKCS 041|JKCS&nbsp;041]] was confirmed to be the most distant [[cluster of galaxies]] yet discovered.<ref>{{cite news|title=Scientists identify new |url=http://www.metro.co.uk/news/756711-scientists-identify-new-galaxy|newspaper=Metro|date=23 October 2009}}</ref> The [[Pisces–Cetus Supercluster Complex]] is a galaxy filament that is one of the [[List of largest cosmic structures|largest known structures]] in the observable Universe; it contains the [[Virgo supercluster]] which contains the [[Local Group]] of Milky Way and other galaxies.<ref name="tully86">{{Cite journal |last=Tully |first=R. B. |date=April 1986 |title=Alignment of clusters and galaxies on scales up to 0.1 C |journal=The Astrophysical Journal |language=en |volume=303 |pages=25 |bibcode=1986ApJ...303...25T |doi=10.1086/164049 |issn=0004-637X}}</ref>

The massive [[cD galaxy]] [[Holmberg 15A]] is also found in Cetus; as are the spiral galaxy [[NGC 1042]], the elliptical galaxy [[NGC 1052]] and the ultra-diffuse galaxy [[NGC 1052-DF2]].

[[IC 1613]] ([[Caldwell catalog|Caldwell]] 51) is an irregular [[dwarf galaxy]] near the star 26 Ceti and is a member of the Local Group.

[[NGC 246]] (Caldwell 56), also called the "Cetus Ring",<ref>{{Cite book |last=Levy |first=Daniel H. |title=Deep Sky Objects: The Best And Brightest from Four Decades of Comet Chasing |publisher=[[Prometheus Books]] |year=2011 |location=United States |pages=129 |language=en}}</ref> is a [[planetary nebula]] with a magnitude of 8.0 at 1600 light-years from Earth. Among some amateur astronomers, NGC 246 has garnered the nickname "Pac-Man Nebula" because of the arrangement of its central stars and the surrounding star field.{{sfn|Levy|2005|p=129}}

The [[Wolf–Lundmark–Melotte]] (WLM) is a barred irregular galaxy discovered in 1909 by [[Max Wolf]], located on the outer edges of the Local Group. The discovery of the nature of the galaxy was accredited to [[Knut Lundmark]] and [[Philibert Jacques Melotte]] in 1926.

UGC 1646, which is a spiral galaxy, also lies between the borders of the constellation. It is about 150 million light-years away from us. It can be seen near TYC 43-234-1 star.<ref>{{Cite web |title=UGC 1646 |url=https://simbad.cds.unistra.fr/simbad/sim-basic |access-date=2024-01-01 |website=simbad.cds.unistra.fr}}</ref><ref>{{Cite web |title=JWST Feed - Target Name: 2MASS-11595807+2807159 Title: JWST Routine Wavefront Sensing and Control for Cycle 2 Instrument: NIRCAM/IMAGE Filters: F356W Start Time: 12/21/2023 10:06:59 AM Obs Time: 85.894(s) Proposal ID: 4504 |url=https://jwstfeed.com/PostView/FeedPost?ci=1703170622_jw04504-o196_t040_nircam_clear-f356w-nrcalong_wfscmb-04 |access-date=2024-01-01 |website=jwstfeed.com |language=en}}</ref>

[[File: Hubble explores explosive aftermath in NGC 298 (potw2322a).jpg|right|thumb|The spiral galaxy NGC 298 basks in this image from the NASA/ESA Hubble Space Telescope. NGC 298 lies around 89 million light-years away in the constellation Cetus, and appears isolated in this image — only a handful of distant galaxies and foreground stars accompany the lonely galaxy.]]

==History and mythology==
[[File:Sidney Hall - Urania's Mirror - Psalterium Georgii, Fluvius Eridanus, Cetus, Officina Sculptoris, Fornax Chemica, and Machina Electrica.jpg|thumb|Cetus dominates this card from ''[[Urania's Mirror]]'' (1825) as if looking up towards the celestial sphere (east is left of frame).  Uses the modern custom: celestial maps to be held skywards while facing south.]]
[[File:Alexander Jamieson Celestial Atlas-Plate 23.jpg|thumb|An alike depiction from ''Celestial Atlas'' (A. Jamieson) (1822)]]
Cetus may have originally been associated with a [[whale]], which would have had mythic status amongst Mesopotamian cultures. It is often now called the Whale, though it is most strongly associated with [[Cetus (mythology)|Cetus the sea-monster]], who was slain by [[Perseus]] as he saved the princess [[Andromeda (mythology)|Andromeda]] from [[Poseidon]]'s wrath. It is in the middle of "The Sea" recognised by mythologists, a set of water-associated constellations, its other members being [[Eridanus (constellation)|Eridanus]], [[Pisces (constellation)|Pisces]], [[Piscis Austrinus]] and [[Aquarius (constellation)|Aquarius]].<ref name="staal">{{Harvnb|Staal|1988|pp=33–35}}</ref>

Cetus has been depicted in many ways throughout its history. In the 17th century, Cetus was depicted as a "dragon fish" by [[Johann Bayer]], while both [[Willem Blaeu]] and [[Andreas Cellarius]] depicted Cetus as a whale-like creature in the same century. However, Cetus has also been variously depicted with animal heads attached to a piscine body.<ref name="staal"/>

===In global astronomy===
In [[Chinese astronomy]], the stars of Cetus are found among two areas: the [[Black Tortoise|Black Tortoise of the North]] (北方玄武, ''Běi Fāng Xuán Wǔ'') and the [[White Tiger (Chinese astronomy)|White Tiger of the West]] (西方白虎, ''Xī Fāng Bái Hǔ'').

The [[Tukano]] and [[Kobeua people]] of the Amazon used the stars of Cetus to create a [[jaguar]], representing the god of hurricanes and other violent storms. Lambda, Mu, Xi, Nu, Gamma, and Alpha Ceti represented its head; Omicron, Zeta, and Chi Ceti represented its body; Eta Eri, Tau Cet, and Upsilon Cet marked its legs and feet; and Theta, Eta, and Beta Ceti delineated its tail.<ref name="staal"/>

In [[Hawaii]], the constellation was called ''Na Kuhi'', and Mira (Omicron Ceti) may have been called ''Kane''.{{sfn|Makemson|1941|p=281}}

==Namesakes==
[[USS Cetus (AK-77)]] was a [[United States Navy]] [[Crater class cargo ship]] named after the constellation.

==See also==
* [[Cetus (Chinese astronomy)]]
* [[Book of Jonah]]

==References==
{{Reflist}}

==Bibliography==
* {{cite book |first = David H. |last = Levy |title = Deep Sky Objects |publisher = [[Prometheus Books]] |year = 2005 |isbn = 1-59102-361-0 |url-access = registration |url = https://archive.org/details/deepskyobjects00davi }}
* {{cite book
  | last = Makemson
  | first = Maud Worcester
  | year = 1941
  | publisher = [[Yale University Press]]
  | title = The Morning Star Rises: an account of Polynesian astronomy
  | bibcode = 1941msra.book.....M
 }}
* {{citation |title = Stars and Planets Guide |last1 = Ridpath |first1 = Ian |last2 = Tirion |first2 = Wil |year = 2001 |publisher = Princeton University Press |isbn = 0-691-08913-2}}
* Ian Ridpath and Wil Tirion (2007). ''Stars and Planets Guide'', Collins, London. {{ISBN|978-0-00-725120-9}}. Princeton University Press, Princeton. {{ISBN|978-0-691-13556-4}}
* {{cite book |first = Julius D.W. |last = Staal |title = The New Patterns in the Sky |publisher = The McDonald and Woodward Publishing Company |year = 1988 |isbn = 0-939923-04-1 }}

==External links==
{{Commons}}
{{Wiktionary|cetus}}
* {{cite EB1911|wstitle=Cetus |volume=5 |short=x}}
* [http://www.allthesky.com/constellations/cetus/ The Deep Photographic Guide to the Constellations: Cetus]
* [http://astrojan.nhely.hu/cetus.htm The clickable Cetus]
* [http://www.ianridpath.com/startales/cetus.html Ian Ridpath's Star Tales – Cetus]
* [https://iconographic.warburg.sas.ac.uk/category/vpc-taxonomy-017081 Warburg Institute Iconographic Database (medieval and early modern images of Cetus)]

{{Stars of Cetus}}
{{Constellations}}
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[[Category:Cetus| ]]
[[Category:Constellations]]
[[Category:Equatorial constellations]]
[[Category:Constellations listed by Ptolemy]]
[[Category:Fictional cetaceans]]
[[Category:Mythological mammals]]