From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide
"Astronomy of the Twelve Colonies" is a document written by the Re-imagined Series scientific advisor Kevin Grazier in 2005 concerning the astronomy of The Twelve Colonies Of Kobol based on Ronald D. Moore's "series bible" and the first two scripts of "33" and "Water". The document helped in the creation of a chapter of The Science of Battlestar Galactica, Bob Harris's book Beyond Caprica: A Vistor's Pocket Guide To The Twelve Colonies, and the Quantum Mechanix product Battlestar Galactica Map of the 12 Colonies.
- Later, when I was working on the chapter about planets for the book Science of Battlestar Galactica, I revisited that document – expanding upon it for the book. While I was writing that chapter I had a conversation with Jane and we agreed that it might serve the dramatic needs of Caprica if we laid out the Colonies explicitly before they got too deep into writing.
- Libra is the only non-animal in the Zodiac (which means "ring of animals"), and is a relative newcomer to the Zodiac – it was created from the pincers of Scorpius that were "clipped off" to create a new constellation. The purpose was to create a one-to-one correspondence between the signs of the Zodiac and months of the year. It turns out that, if we define the Zodiac as the constellations through which the sun passes, then there are 13 signs. After our sun skims the top of Scorpius, and before it enters Sagittarius, it passes through Ophiuchus ("The Serpent Bearer"). If you are born between November 30th and December 17th, you're actually an Ophiuchi. It might be a nice quirky twist to have no colony called named for Libra, but one for Ophiuchus instead-with the constellation Libra being a later Terran cultural influence on the Zodiac.