Some people believe, or make-believe, that the current sign of the zodiac affects how things go in their everyday lives, depending on the sign of their birth. This idea is called astrology, and people who claim to use the signs of the zodiac to make predictions are called astrologers.
No one has shown that astrology can be used to predict the future or describe what people are like based only on their birth date. Still, like reading fantasy stories, many people enjoy reading their "astrological forecast" or "horoscope" in the newspaper every day. Western astrology is based on the 12 signs of the zodiac; Chinese astrology is based on a 60-year cycle and lunar calendar.
In past centuries astrology often relied on close observation of astronomical objects, and the charting of their movements, and might be considered
a protoscience in this regard. In modern times astrologers have tended to rely on data drawn up by astronomers and set out in a set of tables called
an ephemeris, which shows the changing positions of the heavenly bodies through time. It is the interpretation of these science based tables that makes
astrology a target for the label pseudoscience.
Western astrology is the system of astrology most popular in Western countries. Western astrology originated in Mesopotamia during the 2nd millennium BC, from where it spread to much of the world. After spreading to Egypt, where further developments occurred, it then arrived into Greek or Hellenistic culture, where the Greek astronomer and astrologer Ptolemy in his work Tetrabiblos laid the foundations of the Western tradition. Western astrology is largely horoscopic, that is, it is largely based on the construction of a horoscope for an exact moment in time, such as a person's birth, in which various cosmic bodies are said to have an influence. In modern Western sun sign astrology, only the location of the Sun is considered.
During the Dark Ages in Europe knowledge of astrology was lost along with much other learning. It was revived and extended by Arab and Persian scholars and reimported into Europe in the Middle Ages. In medieval Europe, important political and military decisions were often made in consultation with astrologers. Nowadays, believers in astrology use it primarily for making personal decisions or attaining information about an individual through natal astrology. Today, astrology has become distinct from astronomy and mainstream scientists in general dismiss astrology as a form of pseudoscience.
The zodiac
is the belt or band of constellations through which the Sun, Moon, and planets move on their journey across the sky. Astrologers noted these constellations
and so attached a particular significance to them. Over time they developed the system of twelve signs of the zodiac, based on twelve of the constellations
they considered to be particularly important. Most western astrologers use the tropical zodiac beginning with the sign of Aries at the Northern hemisphere
Vernal Equinox always on or around March 21 of each year. Due to a phenomenon called precession of the equinoxes , (whereby the map of the night sky
has changed over time), the portion of sky occupied by each of the zodiac signs no longer corresponds to that of the constellations. For this reason
some Western astrologers use the Sidereal zodiac which still uses the actual star positions.
In modern Western astrology the signs of the zodiac are believed to represent twelve basic personality types or characteristic modes of expression. The twelve signs: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces are divided into four elements fire, earth, air and water. They are also divided into three qualities, cardinal, mutable and fixed. The personality traits of the twelve signs are as follows: