Source One
Trying to identify people's predisposition to a profession physicist J. [MacJervie] researched the distribution of dates of birth of 17,000 scientists and 6,000 political leaders relative to zodiac signs. It also turned out to be completely random. Psychologist B. Silverman from the University of Michigan studied the influence of the zodiac sign corresponding to the birth of each of married couples and the probability of their marriage or divorce. Data about 2987 weddings and 478 divorces were used. The scientist compared the real information with the predictions of two independent astrologers against a favorable or unfavorable combination of zodiac signs for the married couples. It turned out that there was no coincidence between the predictions and reality and therefore Silverman concluded: "The position of the sun in the zodiac at the moment of birth does not exert an influence on the formation of personality".
Astrologers themselves often refer to the works of Parisian statistician M. Gauquelin for a justification of their craft. Gauquelin studied archival data containing the date, time, and place of birth of 41,000 European residents, among them 16,000 famous scientists, artists, writers, athletes, etc. He compared the positions of the planets and constellations at the moment of a person's birth with his personality type and kind of occupation. Those who are not too lazy to read Gauquelin's conclusions will find out that the horoscopes were completely wrong: there was no connection between the character and the personality of a person on the one hand and, on the other, his zodiac sign (that is, the season of birth) and the position of the planets in houses (that is, their height above the horizon) and also their mutual aspects (that is, angular distances) at the moment of birth. Therefore Gauquelin consigned astrology to the ranks of conjecture.
Astrologers themselves often refer to the works of Parisian statistician M. Gauquelin for a justification of their craft. Gauquelin studied archival data containing the date, time, and place of birth of 41,000 European residents, among them 16,000 famous scientists, artists, writers, athletes, etc. He compared the positions of the planets and constellations at the moment of a person's birth with his personality type and kind of occupation. Those who are not too lazy to read Gauquelin's conclusions will find out that the horoscopes were completely wrong: there was no connection between the character and the personality of a person on the one hand and, on the other, his zodiac sign (that is, the season of birth) and the position of the planets in houses (that is, their height above the horizon) and also their mutual aspects (that is, angular distances) at the moment of birth. Therefore Gauquelin consigned astrology to the ranks of conjecture.
Source Two
Uses testable ideas?
Some expectations generated by astrology are so general that any outcome could be interpreted as fitting the expectations; if treated this way, astrology is not testable. However, some have used astrology to generate very specific expectations that could be verified against outcomes in the natural world. For example, according to astrology, one's zodiac sign impacts one's ability to command respect and authority. Since these traits are important in politics, we might expect that if astrology really explained people's personalities, scientists would be more likely to have zodiac signs that astrologers describe as "favorable" towards science.1 If used to generate specific expectations like this one, astrological ideas are testable.
Relies on Evidence?
In the few cases where astrology has been used to generate testable expectations and the results were examined in a careful study, the evidence did not support the validity of astrological ideas.2 This experience is common in science — scientists often test ideas that turn out to be wrong. However, one of the hallmarks of science is that ideas are modified when warranted by the evidence. Astrology has not changed its ideas in response to contradictory evidence
Involves the scientific community?
Sharing one's findings and critically evaluating the results of others are not integral parts of practicing astrology. An astrologer can go his or her entire career and not present findings at a scientific meeting or publish a single article. When astrologers do publish, these articles are not usually peer-reviewed or published in places where they will be critically scrutinized by the scientific community.
Astrology is not a very scientific way to answer questions. Although astrologers seek to explain the natural world, they don't usually attempt to critically evaluate whether those explanations are valid — and this is a key part of science. The community of scientists evaluates its ideas against evidence from the natural world and rejects or modifies those ideas when evidence doesn't support them. Astrologers do not take the same critical perspective on their own astrological ideas.