Astrology used as a medium to both determine one's personality traits and future events is based on the alignment of stars and planets. The most basic form of astrology uses the 12 signs of the Zodiac and the date of one's birth to make predictions. If someone is born between January 20th and February 18th their sun sign is Aquarius. Based on the time of birth, an individual is connected with asun sign.
Many experienced astrologers claim that the use of sun signs is too generalized and not completely accurate. The position of the sun and planets at the date, place and time of a birth are used to give a more specific prediction.
Whether an astrologer uses the simple method or more complex style of prediction makes no difference. The predictions given are generalized descriptions of personality traits that could apply to many. Salesmen, psychics, politicians, therapists and astrologers knowing or unknowingly use a profiling technique called cold reading.
Newsstand horoscopes that use sun signs portray extremely vague descriptions. A Gemini, for instance is described as energetic, clever, imaginative, witty and adaptable. A Taurus is dependable, persistent, loyal, patient and generous. Generic descriptions at affordable prices.
The real cold reading is done when a medium is speaking to individuals or crowds. Astrologers and psychics will make general statements and leave the interpretation up to the recipient. The medium focuses on the individual's reaction to the claims made. They will make more specific predictions as more confirmation is given. Wrong predictions are quickly ignored and an individual is given the illusion that the medium is indeed a psychic.
The test for true prophecy is accuracy without foreknowledge. Old Testament Messianic prophecy is an excellent example. However, astrologers and psychics use a common manipulation technique to make their predictions. Accuracy can only be given in astrology based off data and observation gathered by the medium. Science has determined that the alignment of heavenly bodies has absolutely no effect on human nature. The bottom line is, astrologers and psychics have not past the legitimacy test.