Why does the time of the sunset change?
Because the Earth’s axis is tilted relative to the plane of our orbit, the Sun appears to move north and south of the equator during the cycle of the seasons. So the Sun apparent location also changes at sunrise and sunset. Near the Summer Solstice (June 22 in the northern hemisphere, December 22 in the southern hemisphere) the Sun appears to rise early and set later than usual, while on dates near the winter solstice, the Sun rises later and sets earlier.
