Answer: Earth's rotation on its axis
Step-by-step explanation:
The Earth rotates on an imaginary line called the axis. The side of the Earth that faces the Sun has day, while the side which is away, experiences night. When the Sun appears to move across the sky, it is caused due to rotation of the Earth. It completes in 24 hours.
The revolution of the Earth is too slow for the human eye to comprehend. The Earth completes one revolution in 365 days, thus it causes change in years.
The Sun's revolution and its tilt is not visible to us due to the enormous amount of distance between the Earth and the Sun. The Sun is many light years away from us, making it impossible for us to comprehend the changes that happen on it.