Day and night on Earth are caused by the planet's rotation on its axis. Earth spins around an imaginary line called its axis once every 24 hours. When a part of Earth is facing the Sun, it experiences daylight, which we call day. At the same time, the opposite side of Earth faces away from the Sun and is in darkness, experiencing night. As Earth continues to rotate, different parts of the planet move into and out of sunlight, creating the cycle of day and night

. This rotation makes the Sun appear to rise in the east, move across the sky, and set in the west, although the Sun itself is not moving relative to Earth. The length of day and night changes slightly throughout the year due to Earth's tilted axis and its orbit around the Sun, but the fundamental cause of day and night is Earth's 24-hour rotation