And Phillip I. Johnson, a salesperson at Seventh Sign bookstore, says the business in astrology books, readings and charts is brisk.

"They're serious," he says of the astrology customers. "They talk astrology to each other.... People call and ask how long a certain planet is going to be in retrograde."

Johnson himself says a quote in an astrology book stocked by the store convinced him of the practice. "We have a book here with a quote from Einstein, who I have a phenomenal amount of respect for. If Einstein says it, I have to believe it," he says.

But even as customers snap up scholarly tomes and not-so-scholarly works on astrology, much about its origins and practice remain shrouded in mystery.

Astrology might have originated in ancient beliefs about the procession of the day, Newman says.

"It possibly is related to an ancient Egyptian idea that as the heavens rise during the day it is equivalent to birth, middle age, old age and death," he says.

Astrology today has an equivalent to this formulation in the use of middle, low, ascendant and descendent positions of the sun in predictions, Newman says.

But astrology as we know it, he says, came together when ancient Babylonian astrology, which focused on omens predicting the fates of nations, united with Greek scientific traditions.

"Astrology as you and I know it as a supposedly predictive science only comes into existence around the third or second century B.C.," he says.

Through the Middle Ages, he says, astrology survived as a scientific practice, often in monarchies which employed court astrologers for the sovereign and country. Major decisions of national policy were often decided based on the stars, he says.

Astrology fell into disfavor beginning in the 15th century, he says, but pockets of belief existed even with the rise of astronomy. The famous astronomist Johannes Kepler, for instance, was a convinced astrologer.

The current practice of astrology is a melange of the ancient methods with today's high-tech science, as predictive astrology now uses up-to-date computer systems to design charts.

The original science of astrology was based on the rotation of the sun around the earth, Newman says. The sun was supposed to travel an elliptic path around the planet, and the zodiac is simply a band along that elliptic divided into 12 parts. The zones at that time were named for the 12 different constellations in the zodiac.

A person's destiny and character was supposed to be set by the movements of the planets, sun and moon through the 12 zones of the zodiac and the position of the heavenly bodies at the moment of birth.

"The more fundamental idea," Newman says, "is that the planets and stars have rays they send forth" which affect those born under them.