astrologia
Zodiac
The zodiac is the imaginary band of sky along which the Sun, the Moon and the planets seem to move, divided into twelve signs of 30° each. It is the foundation of Western astrology and originates in Babylonian astronomical observations (second millennium BC), transmitted to the Greek world through Mesopotamia and Egypt.
The twelve signs
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces. Each sign covers 30° of the zodiac. The sum is 360°. The progression follows the seasons of the northern hemisphere: Aries begins with the spring equinox (21 March).
Tropical and sidereal zodiac
Western astrology uses the tropical zodiac, tied to the seasons, in which Aries begins with the spring equinox. Indian (Vedic) astrology uses the sidereal zodiac, tied to the actual position of constellations: due to the precession of the equinoxes, the two systems are now about 24° out of step. The same birth date can yield different signs in the two systems.
FAQ
What is the "precession of the equinoxes"?
A slow movement of the Earth that gradually shifts the apparent position of stars relative to the seasons. For this reason the sidereal and tropical zodiacs have separated.
Do "thirteen signs" exist?
Astronomically there is also Ophiuchus, a constellation crossed by the Sun. Tropical astrology works with twelve 30° signs, not with real constellations.
Which signs match best?
In classical theory: signs of the same element (triplicity) or of complementary elements (Fire-Air, Earth-Water). In real practice, communication and respect count above all.