The Sun sets 23.5 degrees lower than the celestial equator during the solstices. This is because the Earth's axis is tilted at 23.5 degrees, and during the solstices, the Earth's tilt is maximally pointed towards or away from the Sun.

Here's why:

* Summer Solstice: In the Northern Hemisphere, the Sun reaches its highest point in the sky, and the North Pole is tilted towards the Sun. At the summer solstice, the Sun sets 23.5 degrees above the celestial equator for observers in the Northern Hemisphere. This is because the celestial equator is 23.5 degrees below the horizon at that point.

* Winter Solstice: In the Northern Hemisphere, the Sun reaches its lowest point in the sky, and the North Pole is tilted away from the Sun. At the winter solstice, the Sun sets 23.5 degrees below the celestial equator for observers in the Northern Hemisphere. This is because the celestial equator is 23.5 degrees above the horizon at that point.

Important Note: These values are for observers at the equator. The angle of sunset relative to the celestial equator will change depending on your latitude.