Cancer
This portal was curated by:

CANCER

KARKINOS (Carcinus) was a giant crab which came to the aid of the Hydra in its battle with Herakles at Lerna. The hero crushed it beneath his foot but as a reward for its service the goddess Hera placed it amongst the stars as the constellation Cancer.
DATABASES
KARKINOS (Carcinus) was a giant crab which came to the aid of the Hydra in its battle with Herakles at Lerna. The hero crushed it beneath his foot but as a reward for its service the goddess Hera placed it amongst the stars as the constellation Cancer.
In mythology, Cancer is associated with the crab in the story of the Twelve Labours of Heracles (represented by the Hercules constellation). In the myth, Hera sends the crab to distract Hercules while the hero is fighting the Lernaean Hydra, the serpent-like beast with many heads and poisonous breath, represented by Hydra constellation. When the crab tries to kill Hercules, Hercules kicks it all the way to the stars.

In another version, the crab gets crushed instead and Hera, a sworn enemy of Hercules, places it in the sky for its efforts. However, she places the crab in a region of the sky that has no bright stars, because despite its efforts, the crab was not successful in accomplishing the task. Cancer does not have any stars brighter than fourth magnitude.
Cancer was a creature sent by Hera to destroy Heracles, one of Zeus' illegitimate children whom she hated the most. This giant crab latched on to Heracles foot as he was battling the Hydra. He already had his hands full as everytime he cut off one of the Hydra's heads, two more grew in it's place. Before finishing off the Hydra, he turned his attention to the crab and crushed it.

As a reward for the crab's obedience and sacrifice, Hera placed it's image among the stars.
Cancer was first recorded by Ptolemy in the 2nd century AD in Almagest, under the Greek name Καρκίνος (Karkinos).[18]

Showing but few stars, and its brightest stars being of only 4th magnitude, Cancer was often considered the "Dark Sign", quaintly described as black and without eyes. Dante, alluding to this faintness and its culmination at midnight (thus visibility the whole night) in a Northern Hemisphere winter month, wrote in Paradiso:

Then a light among them brightened,
So that, if Cancer one such crystal had,
Winter would have a month of only a day.

Cancer was the backdrop to the Sun's most northerly position in the sky (the summer solstice) in ancient times, or from a forces perspective, the earth's sun-facing side happens to be maximally tilted towards the south. This position now occurs in Taurus due to the precession of the equinoxes, around June 21. This is also the time that the Sun is directly overhead at 23.437°N (rounded), its precise parallel now known as the Tropic of Cancer.[1]

In Greek mythology, Cancer is identified with the crab that appeared while Heracles fought the many-headed 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.[20]