As an interesting side note, we should mention something remarkable about Ophiuchus. This constellation, also known as the "serpent bearer" (pede Serpentarii in Latin), lies fairly close to the ecliptic, the path through the sky along which the Sun moves. (How can we tell where the Sun is if we can't see the stars while it shines? Well, we can study the stars each night and note which ones are overhead at midnight. On the other side of the planet, the Sun is directly overhead, so our star chart will tell us where among the stars it is. By doing this process throughout the year, ancient astronomers were able to see that the Sun moves through the constellations, coming back to where it started every year, in a little more time than it took the Moon to go through all its phases twelve times. Our word "month" comes from "Moon"; this is why we have twelve months in a year, and the different lengths they have happens because the year is a little longer than twelve Moon-cycles.) The ancient Babylonians, who lived in the land which is now Iraq, were among the most sophisticated astronomers and mathematicians in the ancient world. The Greeks picked up many ideas from the Babylonians, nifty inventions like the sundial, plus theoretical ideas about the Sun and planets. One Babylonian idea the Greeks took for themselves was a plan for dividing the sky, roughly based upon the constellations they saw in it. The Babylonian astronomers divided the celestial sphere into twelve "houses", something like slicing an orange into wedges. They named each "house" based upon a prominent constellation they saw near the ecliptic in that house, so each section got a name.
The Greeks named their constellations after characters in their myths and legends. When they learned about the Babylonian system for dividing up the sky, they called it "the circle of little animals", because most of the constellations they saw running around the ecliptic looked like animals. They had Scorpio, the scorpion; Pisces, the fish, and so on. In Greek, "circle of little animals" was zodiakos kyklos. (You can see the same Greek root words in "zoology", the study of animals, "cycle" for something going in a circle, and "bicycle" for a machine with two circular wheels.) From zodiakos kyklos we get our word "zodiac". The Greeks split the year into twelve "signs", each one named for the part of the "animal circle" the Sun was located within during that part of the year. This is the basis of astrology and all the horoscopes we find in our newspapers, even today.
Astrology has many problems, and is probably the most laughable of all the pseudosciences that try to sound scientific without having any real basis. Most people born on the same day don't turn out the same way. Thinking that one-twelfth of the entire world's population is having the same kind of day, every day of their lives, is more than humorous. Given the same date and place of birth, two different astrologers always cast two entirely different horoscopes, unless the horoscopes are so vague they can't be told apart (a useful trick: if the description is vague enough, it can apply to anybody). No one has found legitimate forces which can reach from the planets and affect people in anything like the way astrologers say. For example, the gravitational force of the doctor delivering a baby is roughly a million times stronger than the planet Jupiter's gravitational pull on that same child. The astronomer and writer Carl Sagan once observed that astrology is a doctrine akin to racism and sexism, since it ignores the differences among human beings.
The pseudoscience of astrology has made many people in the modern world relatively wealthy. In past years, too, it was a means for astronomers to support themselves: Johannes Kepler might never have discovered his Laws of planetary motion, if the aristocrats of Europe hadn't been willing to pay for horoscopes. There exists an intriguing possibility, which a clever person might exploit, for a new and modern astrology system. The first person to build a business inventing horoscopes with this new system may be lucky enough to drive other astrologers out of work, since in the modern world, innovation is so often the key to success. This opportunity arises for the following reason:
During some part of the year, the Sun is in Capricorn, Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, and Sagittarius. It also passes through Ophiuchus. If you were born between November 30 and December 17, you are in fact an Ophiuchid, and you can be proud of it.
The Griffith Observatory has a clear introduction to zodiac-related issues.
Tom Robbins's 1976 novel Even Cowgirls Get the Blues contains a reference to the missing thirteenth zodiacal constellation.
What is the numerical significance of the Clock People's taking thirteen months to structure their ritual, then separating into thirteen families? Well, briefly, they consider thirteen a more natural number than twelve. To the ancient Babylonians, thirteen was unlucky. That is why, when they invented astrology, they willfully overlooked a major constellation, erroneously assigning to the zodiac only twelve constellations. The Clock People knew nothing of Babylonian superstition, but they knew the stars, and it was partly in an effort to override the unnatural twelve-mindedness of Western culture that they chose to give thirteen its due (p. 188).
Researched, written and maintained by Blake Stacey.