What causes the angle of the sun to change over the year?

The angle of the sun, as observed from a specific location on Earth, changes over the course of the year due to the tilt of the Earth's axis. Earth's axis is tilted at an angle of approximately 23.5 degrees relative to its orbit around the sun. This tilt is responsible for the changing seasons and the variations in the sun's angle in the sky.

As Earth orbits the sun, different parts of the planet receive varying amounts of sunlight at different times of the year. During the summer solstice, one hemisphere (either the Northern or Southern Hemisphere) is tilted toward the sun, resulting in longer days and higher sun angles. During the winter solstice, the situation is reversed, with that hemisphere tilted away from the sun, leading to shorter days and lower sun angles. The equinoxes, which occur around March 20th and September 22nd, mark the times when the Earth's axis is not tilted toward or away from the sun, resulting in roughly equal day and night lengths.