This is one of those things that a frightening number of people casually believe in. Horoscopes are big business and appear in a wide selection of daily newspapers. The idea is that the position of celestial bodies has an effect on our lives here on earth, the position of planets, stars and constellations in the sky is claimed to have a bearing on our lives. There are many different branches of astrology; the one most familiar to us in the west is the signs of the zodiac.
The date on which you are born is supposed to determine which sign you are. This provides the first problem with the idea, why is it the time of birth as we record it? Why not the moment of conception, after all you exist in some form for nine months before you actually pop out?
Horoscopes for different signs of the zodiac provide the most obvious flaw in the belief system as generalised advice based on your sign is offered but we know that the only way these messages can apply to such a wide range of people as for example all those born between May 21st and June 21st is by making the advice so generalised that it could apply to anyone. It should be fairly obvious that a twelfth of the world do not have the same experience or feelings each day.
The scientific community rejects astrology as mere superstition because there is no evidence to support it and a number of controlled studies have failed to provide any.
The western system of astrology is especially flawed; our planets are named after Roman gods whom we have no belief in, the system was developed when people still believed the earth was the centre of the universe and we ignore the 13th sign of the zodiac even although older branches of astrology were happy to include it.
It is also worth pointing out that due to precession the earth is no longer aligned the same way as it was with the stars but the assignment of star signs has not changed to compensate.
Sadly those who believe in astrology as more than just a bit of fun do so with a religious faith and so they are unlikely to be swayed by arguments based on common sense. They often argue that it is harmless and many astrologers just give good advice but there are no checks at all on the advice they are giving and some people are fool enough to live their lives by it. If you think it is harmless consider this, someone as powerful as the President of the United States Ronald Reagan based many of his plans on astrology, he relied on it to make important decisions which effectively means he was taking advice from a series of women who called themselves astrologers. We may even have them to blame for the ascendancy of the Bush family since George Bush Senior was apparently chosen as his Vice President from a list of seven candidates because he was a Gemini.
People continue to believe in astrology despite the lack of evidence. There have been tests to examine whether there is any correlation between birth signs and personality as astrology claims there is and the results clearly show the idea is completely false, there is absolutely no link between when you are born and what your personality is like. Tests which allow astrologers to read personal charts in greater detail have also proved their complete lack of ability to determine things about those people, when they give good or accurate advice it is more likely they are doing so by reading body language and questioning their customers, essentially they are cold reading.