An Etymological Dictionary of Astronomy and Astrophysics

The Crab. The dimmest → constellation of the → Zodiac, located in the northern hemisphere at approximately R.A. 8 h and Dec. +20°. The main feature of the constellation is the open cluster → Praesepe (M 44). Abbreviation: Cnc; genitive form: Cancri.

Etymology (EN): Cancer,from L., from Gk. karkinos; PIE base *qarq- “to be hard” (like the shell of a crab); cf. Skt. karkatah “crab,” karkarah “hard."
In Gk. mythology the Crab was sent by the goddess Hera to bite Hercules in the midst of the struggle with → Hydra, but Hercules crushed the crustacean
with his heel. Hera rewarded the Crab by placing it in the → Zodiac.

Etymology (PE): Xarcang “crab,” from Mid.Pers. karcang, cf. Lori qerženg from kar-, qer- + cang, ženg “claw.” The component
xar/qer may be related to Av. xruta-, xraoždva- “hard,” as in xruždisma- “hard ground” (from xruždi-

• zam-), and to the PIE *qarq- “to be hard.” In that case, the Pers. term for crab would literally mean “hard claw.”