Editing Cancer (constellation) (section)

==History and mythology==
{{Main|Cancer (mythology)}}
Cancer was first recorded by [[Ptolemy|Claudius Ptolemy]] in the {{nobr|2nd century CE}} in ''The [[Mathematical Syntaxis]]'' (a.k.a. ''[[Almagest]]''), under the Greek name {{math|Καρκίνος}} (''Karkinos'').<ref>{{cite book |first=Ian |last=Ridpath |date=28 June 2018 |title=Star Tales |publisher=ISD LLC |isbn=9780718847814 |url=https://books.google.com/books?id=7dXYDwAAQBAJ&q=karkino+ptolemy+first+recorded&pg=PA57 |via=Google Books}}</ref>

In the late 1890s, [[Richard Hinckley Allen|R.H. Allen]] asserted the following, with no supporting citation:
:"Cancer is said to have been the place for the [[Akkadian Empire|Akkad]]ian ''Sun of the South'', perhaps from its position at the [[solstice|winter solstice]] in very remote antiquity; but afterwards it was associated with the fourth month ''[[Babylonian calendar#Months|Duzu]]{{Broken anchor|date=2024-07-29|bot=User:Cewbot/log/20201008/configuration|target_link=Babylonian calendar#Months|reason= The anchor (Months) [[Special:Diff/1197585795|has been deleted]].}}'' {{grey|[''araḫ Dumuzu'']}}, our June–July, and was known as the ''Northern Gate of Sun''&nbsp;..."<ref>{{cite thesis |first=R.H. |last=Allen |author-link=Richard Hinckley Allen |year=1898 |title=Star Names: Their lore and meaning |page=108 |publisher=[[University of Minnesota]] |place=Minneapolis, MN}} Reprinted 1899 by [[Dover Books]], New York, NY, and continually to the present.
:Quoted nearly verbatim by:
{{cite book |first=W.T. |last=Olcott |author-link=William Tyler Olcott |title=Star Lore of All Ages: A collection of myths, legends, and facts concerning the constellations of the northern hemisphere |place=New York, NY |publisher=G.P. Putnam |year=1911 |page=89 |bibcode=1911slaa.book.....O |postscript=,}} citating Allen (1898/1899).
:Later authors continue to repeat the same quote from Allen (1898/1899) to the present.</ref>

Very few of Cancer's stars are [[Limiting magnitude#In naked-eye visibility|visible to the naked eye]], and its brightest stars are only 4th&nbsp;[[Apparent magnitude|magnitude]]. Cancer was often considered the "Dark Sign", quaintly described as "black and without eyes".{{citation needed|date=June 2022}} [[Dante Alighieri|Dante]], alluded to its faintness in ''[[The Divine Comedy#Paradiso|Paradiso]]'', and mentioned it being visible for the whole night when it [[culmination|culminated]] at midnight in a Northern Hemisphere winter month:

:Then a light among them brightened,
:so that, if Cancer one such crystal had,
:winter would have a month of only a day.<ref>{{cite book |author=Dante Alighieri |author-link=Dante Alighieri |title=[[The Divine Comedy#Paradiso|Paradiso]] |series=[[The Divine Comedy]]}}</ref>{{full citation needed|reason=page, date, publisher, edition|date=June 2022}}

Cancer was the backdrop to the Sun's most northerly position in the sky (the [[summer solstice]]) in ancient times, when the Earth's Sun-facing side was maximally tilted towards the south, in the [[Gregorian calendar]] kept within a few days of June&nbsp;21. Equivalently, this is the date when the Sun is directly overhead as far north as [[obliquity of the ecliptic|23.437°&nbsp;N]]. The northern-most [[parallel (geography)|parallel]] where the Sun is directly overhead is still called the ''[[Tropic of Cancer]]'', even though the corresponding position on the sky now occurs in [[Taurus (constellation)|Taurus]], due to the [[precession of the equinoxes]].<ref name="ridpath"/>

The close [[conjunction (astronomy)|conjunction]] of Jupiter and Saturn in 1563 – which was observed by [[Tycho Brahe]] and led him to note the inaccuracy of existing ephemerides and to begin his own program of astronomical measurements – occurred in Cancer not far from Praesepe.

In [[Greek mythology]], Cancer is identified with the crab that appeared while [[Heracles]] fought the many-headed [[Lernaean Hydra]]. Hercules slew the crab after it bit him in the foot. Afterwards, the goddess [[Hera]], an enemy of Heracles, placed the crab among the stars.<ref>{{cite book |author-link=Gaius Julius Hyginus |author=pseudo-Hyginus |title=[[De astronomia]] |at=2.23}}</ref>