What is the ecliptic?

Astronomy calls the annual apparent trajectory of the sun on the celestial sphere, that is, the great circle of the apparent path of the sun in the sky "ecliptic", that is, the projection of the earth's orbital plane on the celestial sphere. The sun rotates once a year on the celestial sphere along the ecliptic. In order to determine the position, people divide the ecliptic into twelve equal parts (each part is equivalent to 30 parts), and each part is named after an adjacent constellation. These constellations are called the zodiac or the zodiac. This is equivalent to dividing a year into twelve segments, in which the sun enters a constellation. In the west, when a person is born, which constellation the sun is going to, he is said to belong to this constellation.

The angle between the ecliptic and the celestial equator is 23 degrees and 26 minutes (the angle between the ecliptic and the celestial equator); The two intersections of the ecliptic and the celestial equator are the vernal equinox and the autumnal equinox. In the ecliptic coordinate system, the longitude of celestial bodies is measured eastward along the ecliptic from the vernal equinox, with positive north latitude and negative south latitude. The distance between the south and north poles and the corresponding celestial pole is 23 degrees and 26 minutes. Because the earth's revolution is disturbed by the moon and other planets, the orbit of the earth's revolution is also a strict plane, that is, there is an irregular continuous change in space, which includes many short-term events and a slow long-term movement. Short-period motion Yao can be averagely eliminated in a certain period of time, and the stack orbital plane except periodic motion is called instantaneous Planck orbital plane. The strict definition of the ecliptic is: the instantaneous average orbital plane of the earth and the moon around the center of mass of the sun? 3? The great circle where the celestial spheres intersect. The ecliptic is the base circle of the ecliptic system on the celestial sphere.

Because we can only see the sun during the day, but we can't see the stars at this time. So which constellation the sun went to, we just can't see it. In other words, when we celebrate our birthdays, we just can't see our horoscope.