How to calculate declination according to the solar meridian

The formula for calculating declination according to the solar meridian is sinδ= 0.3977sinλ.

The solar ecliptic lasts about 365 days, and at 5: 48: 46, the earth orbits the sun for 940 million kilometers. The revolution of the earth is manifested as the annual apparent motion of the sun for people on the earth, and its running route (that is, the reflection of the earth's orbit on the celestial sphere) is called the ecliptic. The zodiac is the measuring coordinate (longitude) on the ecliptic. According to astronomical practice, it is measured from west to east from the vernal equinox and divided into 360 degrees. The ancients in our country divided the 360-degree longitude of the sun into 24 equal parts, each equal part is 15 degrees, which is a solar term. The interval between two solar terms is about 15 days, and there are 24 solar terms throughout the year.