Explanation of zodiac signs in astrology

The zodiac is determined by the position of the Sun in the sky relative to the 12 constellations and is closely related to astrology.

The 12 zodiac signs are linked to the Earth's movement across the sky. Photo: Wordpress.

The zodiac, or the 12 signs listed in astrology, are linked to the Earth's movement across the sky. Because the Earth revolves around the Sun on a plane, we see the Sun appear and move in front of different constellations throughout the year, according to Earth Sky.

Just as the Moon appears in a slightly different position in the sky each night, the Sun's position relative to distant background stars gradually shifts eastward from day to day. For example, if the Sun is in Gemini this month, it will be in Cancer next month.

The specific dates listed in Western astrology are used to identify when the Sun is in a particular zodiac sign. For example, March 21st to April 19th is the sign of Aries. Nowadays, the zodiac sign you were born in does not necessarily coincide with the name of the constellation the Sun is passing through.

To understand why constellations no longer correspond to their respective zodiac signs, we need to know more about how the Earth moves.

The Earth rotates, and its North Pole doesn't always point in the same direction. Like a spinning top, the Earth wobbles, causing the North Pole to move in a circle across the celestial sphere. This wobble is quite slow, with a cycle of 26,000 years, meaning the Earth doesn't actually complete a full orbit in a year. After about 2,000 years, the Sun will be in a completely different constellation for the same period of time.

On the summer solstice in June 2,000 years ago, the Sun was almost directly between the constellations Gemini and Cancer. But on the summer solstice of 2016, the Sun was between Gemini and Taurus. In the year 4609, the Sun will leave Taurus and move to Aries on the summer solstice.

The zodiac signs, corresponding to the constellations through which the Sun passes, were determined 2,000 years ago. However, by the mid-21st century, the slow wobble of the Earth's rotational axis caused the summer solstice, winter solstice, and spring and autumn equinoxes to shift approximately 30 degrees westward relative to the constellations. Currently, the zodiac signs and constellations are out of alignment by about a month. In about 2,000 years, they will be out of alignment by about two months.

The constellations of the zodiac are not all the same size and shape. Most of them appear in the texts of the ancient Babylonians and were introduced by Ptolemy, the Greek astronomer who lived in the 2nd century.

In 1930, the International Astronomical Union defined the boundaries of modern constellations, encompassing all 13 constellations that lie along the path of the Sun. The constellation not listed in Western astrology is Ophiuchus, located between Sagittarius and Scorpio.

According to VNE