Constellation Legend _ Constellation Legend Gemini

In ancient times, in order to identify the direction and facilitate the observation of the sky, the stars scattered in the sky were connected by imagination, and half of them were named in ancient times, and their naming methods were attached according to the myths and shapes of ancient civilizations.

The other half was named only in modern times, often named after navigation instruments. In ancient times, because of different regions, the way of "Lianliankan" was different! 2 1 century, the world unified the constellation map and divided the sky into 88 regions and 88 constellations.

The "constellation" we usually say refers to the "sun constellation"; That is to say, people on the earth are the center, and at the same time, we can see which constellation the sun is in orbit (Greek zodiac: meaning ~ circle made by animals, also known as "zodiac"), so we can say what constellation that person is.

Extended data:

The movement of constellations

It seems that the movement of the constellation with the celestial sphere is caused by the movement of the earth itself, in which the rotation and revolution of the earth are the most obvious changes in the starry sky. Due to the rotation of the earth, the starry sky background rotates once a day around the celestial axis; The starry sky also changes slowly with the seasons. A year has passed, and the starry sky is almost the same as it was a year ago.

The rotation axis of the earth's rotation also has a long-term motion, called precession, with a period of about 25,765 years. This movement causes the periodic drift of the North Pole in the background of stars, which is called precession in astronomy. A cursory observation of the constellation in a short time can ignore this movement.

The stars are moving at high speed. The motion of stars can be decomposed into the radial velocity of their connection direction and the self-nature perpendicular to it, in which the self-nature will change the apparent position of stars in the starry sky. Because the star is too far away from the earth, it can generally be considered that the position of the star in the sky is fixed.

Because the apparent positions of the sun and planets relative to the earth are not fixed with the positions of the background stars on the celestial sphere, they periodically pass through the 13 constellation on the ecliptic. In astrology, it is often described as "Mercury is in Scorpio". However, there are only twelve constellations in astrology, and they are equally divided.

Baidu encyclopedia-twelve constellations