Question
Why does the duration of day and night change in a year?
Answer
The duration of the day and night changes in a year because the earth is tilted on its axis. As it orbits the Sun, a different part of the earth faces the Sun. When the hemispheres face the Sun, the length of the day is more than night. When the hemispheres are far away from the Sun, it is just the opposite. The nights are longer than days.