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.

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 (where the Earth's axis slowly rotates like a spinning top in a 25,700 year cycle), there is a slow shift in the correspondence between Earth's seasons (and calendar) and the constellations of the zodiac. For this reason some Western astrologers use the Sidereal zodiac which still uses the actual star positions.

Planets

CLASSICAL PLANETS
These are the seven heavenly bodies known to the ancients and are believed to represent the seven basic drives in every individual (the sun and moon, also known as 'the lights', are included in this assessment alongside the planets). Astrologers call Mercury, Venus and Mars the 'personal planets', as they represent the most immediate drives. The 'lights' symbolise respectively the existential and sensitive fundamentals of the individuality. Jupiter and Saturn, until very recently the two furthest planets, represent aspects of the individual functioning as part of society.

* - Sun: Personal strength, vitality and achievement, leadership qualities, power and authority; the need to express oneself; creativity, parenthood, (especially fatherhood), the need for recognition, esteem and personal pride. Ruler of the zodiac sign Leo
* - Moon: Inner feeling, moods, habits, the unconscious, nurturing and parenthood (especially motherhood), femininity, home and family life in general, instinctive reactions to life, need for emotional security and safety. Ruler of the zodiac sign Cancer.
* - Mercury: Mentality, communication, (especially for short distances), thought processes, teaching, schooling and basic education, literary pursuits, the immediate environment or neighborhood, capacity to be logical, detached and rational. Ruler of the zodiac signs Gemini and Virgo.
* - Venus: Relationships and partnerships of all kinds, romantic love, desire for beauty, harmony and co-operation, personal comforts and possessions, the arts, fashions and social life. Ruler of the zodiac signs Taurus and Libra.
* - Mars: Urge for action, personal energy and drive, assertiveness and aggression, sexuality and passions. Sport, physical activity and competition. Ruler of the zodiac sign Aries and traditional ruler of the zodiac sign Scorpio.
* - Jupiter: Personal growth and expansion, aspirations, desire for freedom, sense of justice and morality, religion, philosophy, higher education, the law, long distance communication, enterprise, risk taking and gambling. Ruler of the zodiac sign Sagittarius and traditional ruler of the zodiac sign Pisces.
* - Saturn: Personal limitations and structure, sense of responsibility, ambition, career, authority and hierarchy, serious thought, concern for hard realities of life, capacity for hard work, discipline of self and others, tenacity and trustworthiness, capacity to deal with sickness and difficulties in life. Ruler of the zodiac sign Capricorn and traditional ruler of the zodiac sign Aquarius.

MODERN PLANETS
These are the planets discovered in modern times, which have since been assigned meanings by Western astrologers. Except Ceres, which is considered to be a 'personal' planet because of its rotation and proximity, the other three are considered to be 'impersonal' planets, representing broad trends and impulses in society rather than in the individual.

* - Uranus: Rebellion and unconventionality, breaking down of old structures, new ways of thinking and acting, innovation and invention, idealism and progressive thought, clubs, societies, humanitarian organizations, political movements, need to be unique, unusual, desire for individual self expression and independence. Ruler of the zodiac sign Aquarius.
* - Neptune: Mysticism, transcendence, psychic impulses, feelings of sensitivity and empathy, care of the sick, the mentally ill, animals, charities, religious institutions, hospitals, prisons, retreat from society, artistic inspiration, spirituality, vulnerability to drugs. Ruler of the zodiac sign Pisces.
* or - Pluto: Transformation and regeneration of person's life, beginnings and endings of phases of life, sex, death, issues of power and control, revealing hidden secrets, big business, police, detective and secret services, surgery, mining, extremes of wealth and poverty. Ruler of the zodiac sign Scorpio.
* - Ceres: Women's independence, climactic changes, native needs to feel loved and nurtured, the reproductive issues of an adult woman, pregnancy and gestation, family bonds and relationships. For some astrologers is the ruler of the zodiac sign Virgo.

SOURCE: en.wikipedia.org