de sideribus Cancri

This week I focused on the line from Eclogue X "Aethiopum versemus ovis sub sidere Cancri" (10.68)-- I wanted to see if I could find more information regarding a connection between ancient Ethiopia and the constellation of Cancer. (I also happen to be a July baby and a cancer).

According to Willams' commentary: "'we were to drive the sheep of the Aethiopians beneath the constellation Cancer.' Gallus at the end is indeed thinking of himself as a shepherd. The Aethiopians exemplify the far south; cf Theocritus. Id.7.113. Horace (Odes 1.22.17f) in less serious mood ends his Lalage poem with the picture of his love continuing to be the same if he were transported to the extreme north or the extreme south." (p. 132)

"...in midwinter may you live turned toward the river Hebrus on the mountain of the Edonians, near the pole, but in summer may you pasture your flocks among the furthest Ethiopians beneath the rock of the Blemyes, where the Nile can no longer be seen." (Idylls 7.111-114)

Theocritus, Moschus, Bion. Theocritus. Moschus. Bion. Edited and translated by Neil Hopkinson. Loeb Classical Library 28. Cambridge, MA: Harvard University Press, 2015.

"Put me on a lifeless plain where no tree is refreshed by summer breezes, a part of the world oppressed by fog and sullen skies, set me beneath the chariot of the sun where it comes too close to the earth in a land forbidding houses." (Odes 1.22.17-22)

Horace. Odes and Epodes. Edited and translated by Niall Rudd. Loeb Classical Library 33. Cambridge, MA: Harvard University Press, 2004.

The Theocritan "ends of the earth" are closely modeled in Eclogue 10-- where the river Hebrus represents the far north, and Ethiopia the far south. The sentiment of traversing the ends of the earth for love, requited or otherwise, found in both Theocritus and Horace is also reflected in Eclogue 10. This, however, does not answer my question regarding the constellation of Cancer... 

The constellation of Cancer is one of the oldest recorded constellations, although Ptolemy is usually credited with its first recording. It did not always take the form of a crab-- for the ancient Sumerians it was sometimes a turtle, the Egyptians a scarab. In Greece and subsequently Rome, Cancer was associated with Herakles' second labor, the killing of the Lernaean Hyrda. Hera/Juno sent the crab to distract Herakles from defeating the Hydra-- when the crab pinched his toe he stepped on it, killing it. Hera/Juno felt sorry for the crab so she threw it up to the sky. The Greek word Καρκίνος and Latin, Cancer are cognates meaning crab.  

Cancer appears in the Northern Hemisphere in spring and the Southern Hemisphere in the fall. In modern times it is barely (if at all) visible to the naked eye, but usually has the appearance of an upside-down Y. The constellation is made up of stars and exoplanets, but its most noticeable feature in the sky is Messier 44 or the Beehive cluster-- a densely packed cluster of stars. Messier 44 was noted by many ancient astronomers throughout time. Pliny, in The Natural History mentions this cluster as one of the nebulae, noting that if it was not visible in the night sky a violent storm was on its way (some of the sources I read mention this excerpt from Pliny but I for the life of me could not find it in Book II, which I assumed must be where it comes from?).

On the summer solstice in the Northern Hemisphere the sun passed directly in front of the constellation Cancer-- it no longer does this because of the equinox precession. The equinoctial precession is (very basically) a shift in the intersection between the "ecliptic and celestial equators", most likely first measured by Hipparchus of Nicaea (an astronomer and mathematician writing in the 2nd century BCE-- his works heavily influenced Ptolemy as well as Pliny).  The explanation of a precession is eloquently provided by NASA so I will drop that link here.  Cancer is located between the constellations Leo and Gemini on the ecliptic line. Our summer solstice is now when the sun passes through Taurus which is located next to Gemini on the same line. 

What does this have to do with the Ethiopians? Seemingly nothing. However, if we take "the Ethiopians" in the context of 10.68 to mean the furthest south we perhaps can make sense of the mention of Cancer. As the constellation cancer moves on the ecliptic line in the Northern Hemisphere, it appears to go "southward" in the night sky. Thus, perhaps this movement is another symbol of the ends of the earth. If you follow the constellation cancer in the night sky, you will reach the furthest south in the lands of Ethiopia.

I got the bulk of my information from Nasa and Space.com (here and here) and related but somewhat unrelated, I read a cool article about the origins of the constellations in ancient Mesopotamia if anyone is interested.