How many constellations are there in the sky?

The sun runs from west to east on the ecliptic and circles the sky once a year. There are 12 constellations on a belt on both sides of the ecliptic. They are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces. People on earth can see them one after another in a year.

There are 88 constellations all day. Constellation standard number was formulated by the International Astronomical Union in 1930. The constellation you see in leisure magazines is the famous zodiac. These constellations are just above the ecliptic, which is the only route for the sun in the sky, so it is called the zodiac. And which constellation you belong to depends on which constellation the sun was in when you were born. But all this happened more than two thousand years ago.

More than two thousand years have passed, and the dates of the twelve constellations are no longer consistent with the astronomical phenomena. And because the swing period of the earth's axis is 26,000 years, the position of the ecliptic in the sky is also changing. This periodic oscillation of the earth's axis is called precession. In this way, every two thousand years, the time for the sun to reach each house will be pushed back by about one month. Now the vernal equinox is not in Aries, but has retreated to Pisces. In addition, the ecliptic now not only passes through the twelve constellations, but also praises the thirteen constellations of Ophiuchus.