The solar declination angle, which ranges from -23.45° to 23.45°, is the angle between the sun’s apparent position in the sky and the equatorial plane. It varies throughout the year due to the Earth’s tilt and orbit around the sun. A higher solar declination angle results in the sun being higher in the sky, while a lower angle means it is lower. Accurate calculation of the solar declination angle is crucial for determining the sun’s position and predicting sunrise and sunset times.