Western astrology
Origins
Western astrology originated in Mesopotamia during the 2nd millennium BC, from whence it spread to much of the world. Other systems of astrology were developed independently in China, in the Americas and elsewhere. Premodern observers noticed that the annual patterns of the movement of the stars coincided with such events as the advent of springtime, changes in weather and the migration of birds every year. Without knowing why these phenomena occurred together, other events were said to be affected by the stars as well. In medieval Europe, important political and military decisions were often made in consultation with astrologers. Today, believers in astrology use it primarily for making personal decisions, and astrology has become distinct from astronomy. Mainstream scientists in general dismiss astrology as a form of pseudoscience.
Horoscope
An astrological natal chart or horoscope is based on a person's birth and will show where the stars and planets were positioned in relation to each other at the moment of birth, and the person's specific latitude and longitude at that time. The most prominent of these features is the position of the sun in relation to the signs of the zodiac. The "birth sign" commonly used in Western astrology is actually based on the zodiac of c. 600 BC and is not the constellation the sun was actually located in on the person's birthday. From these planetary positions astrologers draw certain conclusions about the person. Similarly, a horoscope may be prepared to reflect circumstances of an event.
Horoscope interpretation
In Western astrology the interpretation of a horoscope or natal chart is governed by:
astrological aspects: the positions of the major planetary bodies relative to each other,
the major planetary bodies' positions relative to the astrological signs of one of the zodiac sytems,
the major planetary bodies' positions in one of the systems of astrological houses,
their positions relative to the horizon line (namely the ascendant/descendant axes, zenith/midheaven and nadir/imum coeli axes),
the position of deduced astronomical entities, namely the Moon's nodes.
Popular astrology
Newspapers often print astrology columns, which purport to provide guidance on what challenges might be found in a day, as determined by the position of the planets and stars on that day, in relation to the sign of the zodiac that included the sun when the person was born. Professional astrologers refer to this as the "sun sign", but it is often incorrectly called the "star sign" in newspapers. These predictions, an innovation of 20th century newspapers, are vague or general, so that even practising astrologers consider them of little value. Experiments have shown that when people are shown a newspaper horoscope for their own sign along with a newspaper horoscope for a different sign, they judge them to be equally accurate on the average. Professional astrologers claim that a more complete, personalized chart is more effective, but critics claim that this is not the case (see external link to "The AstroTest" below).
Western Sidereal Astrology
There are two camps of thought among western astrologers about the "starting point", 0 degrees Aries, in the Zodiac. Sidereal Astrology believes that the starting point is at a particular fixed position in the background of stars, while Tropical Astrology (which is adopted by the vast majority of Western astrologers) believes that the starting point is when the position of the Sun against the background of stars coincides with the Northern hemisphere vernal equinox (i.e. when the Sun position against the heavens crosses over from the southern hemisphere to the northern hemisphere) each year.
As the Earth spins on its axis, it "wobbles" like a top, causing the vernal equinox to move gradually backwards against the star background, (a phenomenon known as the Precession of the equinoxes) at a rate of about 30 degrees (one Zodiacal sign length) every 2,160 years. Thus the two Zodiacs are aligned only once every 26,000 years, with the most recent alignment being about 2,000 years ago when the zodiac was principally established. This phenomenon gives us the conceptual basis for the Age of Aquarius, whose "dawning" coincides with the movement of the vernal equinox across the cusp from Pisces to Aquarius in the star background.
Western astrological symbols
Astrological symbols (most of these will not display correctly in many browsers):
☄ - Comet
☉ - Sun
☊ - Ascending Node
☋ - Descending Node
☌ - Conjunction
☍ - Opposition
☽ - First Quarter Moon
☾ - Last Quarter Moon
☿ - Mercury
♀ - Venus (Female Sign)
♁ or ⊕ - Earth
♂ - Mars (Male Sign)
♃ - Jupiter
♄ - Saturn
♅ - Uranus
♆ - Neptune
♇ - Pluto
♈ - Aries
♉ - Taurus
♊ - Gemini
♋ - Cancer
♌ - Leo
♍ - Virgo
♎ - Libra
♏ - Scorpio
♐ - Sagittarius
♑ - Capricorn
♒ - Aquarius
♓ - Pisces