#daynight #earth #ngscience
Learn why we experience day and night on Earth in just one minute.
Rotation of the Earth
If you observe the position of the Sun in the sky, you will notice that it rises in the east at dawn, is high in the sky at midday and sets in the west in the evening. This apparent movement is not due to the motion of the Sun, but the motion of the Earth.
One way the Earth moves is by spinning on its axis. The Earth’s axis is an imaginary line that runs from the North Pole, through the Earth’s center, to the South Pole. One complete spin on its axis is called a rotation.
At the equator, the Earth’s spins at about 1,600 kilometers (1,000 miles) per hour. It takes the Earth 24 hours (one day) to complete one rotation.
As the Earth rotates, part of the Earth is facing the Sun. This part of the Earth is lit up and experiences daytime. At the same time, the opposite side of the Earth is facing away from the Sun. This part of the Earth is in darkness and it is night-time.
The rotation of the Earth also causes patterns in the different positions of the Sun in the sky. This results in predictable pattern changes in the length and direction of shadows.
At sunrise, the Sun appears low in the sky. The shadows of the objects that block sunlight in the early morning are long. The shadows get shorter as the Sun rises in the sky. Shadows are at their shortest around midday when the Sun is directly above. Shadows get longer as the Sun moves lower and sets in the west.
19 ноя 2022
