Zodiac

The zodiac is a special area of the sky. It stretches about 8° north and south of the path the Sun appears to follow over the year. This path is called the ecliptic.

The Moon and bright planets also move through this area as they orbit the Sun.

The zodiac is divided into 12 equal parts. These parts are called "signs." Each sign covers 30° of angle across the sky. These signs are linked to 12 groups of stars called constellations. Some of these constellations are named Aries, Taurus, Gemini, and Pisces. People have used these signs for thousands of years to help know the time of year. They look at where the Sun appears in the sky.

The idea of the zodiac began with Babylonian astronomy around the 1st millennium BC. It later spread to Greek astronomy and other cultures. Even today, astronomers use a coordinate system based on the zodiac to track objects in space.

Name

The word zodiac comes from an old Latin term meaning "of or relating to little animals." Many of the twelve zodiac signs are animals or mythical creatures. In English, the word zodiac can also describe a similar idea used in East Asian cultures, called the Chinese zodiac. This system uses twelve animals to represent a cycle of years and is often used to talk about personality traits and life events.

Usage

The zodiac has been used since ancient times, beginning with Babylonian astronomy and later in the Roman era. The astronomer Ptolemy described it in detail in his famous book, the Almagest.

Today, many people know the zodiac from horoscopic astrology. It also describes an area of the sky where planets move, about 8 degrees above and below the path the Sun seems to follow during the year. This area includes the paths of the Moon and planets, and may also include where some comets appear.

History

Further information: Former constellation

The zodiac is a band of sky about 8° wide on either side of the path the Sun appears to follow over a year. It has ancient roots. Early lists of stars and sky patterns come from places like ancient Egypt and Babylon. The idea of dividing this path into twelve equal parts, which we call the signs of the zodiac, began in ancient Babylon around the first half of the first millennium BC. These signs each cover 30° of the sky.

Babylonian astronomers created this system to help track the positions of planets and the Sun. They used bright stars as reference points. Later, this idea spread to other cultures, including Greece, India, and the Islamic world, where it continued to develop and be used in many ways over many centuries.

Twelve signs

Main article: Astrological sign

The zodiac has twelve equal parts, called signs. Each sign covers 30 degrees of the sky and has its own special name. People often remember them with this fun rhyme: "The ram, the bull, the heavenly twins, And next the crab, the lion shines, The virgin and the scales, The scorpion, archer, and the goat, The man who holds the watering-pot, And fish with glittering scales."

The Sun moves through each sign for about the same amount of time, roughly 30 days. The exact time can change a little because of the shape of Earth’s orbit and how it tilts. This means some signs may appear in the sky a bit longer or shorter than others, depending on where you are on Earth.

Constellations

In tropical astrology, the zodiacal signs are different from the actual star patterns, or constellations, they are named after. This is because the Earth's rotation wobbles over time, making the signs move relative to the stars. The constellations are not all the same size, so the Sun spends different amounts of time in each one.

The path the Sun follows in the sky, called the ecliptic, passes through 13 constellations. Along with the twelve constellations that give their names to the zodiac signs, there is also Ophiuchus, which sits between Scorpius and Sagittarius. Some people think this means the zodiac signs have changed, but this is not true. Other star patterns are sometimes linked to the zodiac in different ways.

Precession of the equinoxes

Further information: Axial precession, Epoch (astronomy), Sidereal and tropical astrology, Astrological age, and Ayanamsa

The zodiac system started in Babylonia about 2,500 years ago. It began during a time called the "Age of Aries." At that time, people did not know about the precession of the equinoxes, a slow wobble in Earth's axis.

Today, the zodiac can be used in two ways. In Western astrology, the signs are linked to the Sun's position at the March equinox, called the tropical zodiac. In Hindu astrology, the signs are linked to the stars' background, called the sidereal zodiac. Because of the precession of the equinoxes, these two systems slowly move apart, shifting about 1.4 degrees every century.

This shift means that while the tropical sign Aries is used in Western astrology, it now actually lies within the constellation Pisces. This change is tied to something called the ayanamsa, which tracks the movement of the equinoxes.

In modern astronomy

The zodiac is an area of the sky that extends about 8° to the north and south of the ecliptic. This is the path the Sun appears to take over the year. The Moon and planets also move within this area.

The zodiac is divided into twelve equal parts, called signs, each covering 30°. These signs include Aries, Taurus, and others up to the twelfth sign. Even though these signs have special names, they do not match the actual star patterns, or constellations, nearby. Today, astronomers usually measure positions in the sky using a different system based on Earth’s axis, rather than the zodiac. The term “zodiac” is also used for a dusty glow in the sky called the zodiacal light, caused by tiny particles scattering sunlight.

Unicode characters

In Unicode, the symbols for the zodiac signs are found in a special area called "Miscellaneous Symbols". You can make these symbols look like normal text by adding a special code called U+FE0E. If you add another code, U+FE0F, they will look like colorful emojis instead.