Why We Have Day and Night

Every day, the Sun rises in the morning and sets in the evening. This happens because Earth is spinning. The side of Earth facing the Sun has daytime. The other side, facing away from the Sun, has nighttime. Earth makes one full spin every 24 hours.

How Earth Spins

Earth spins around an imaginary line called its axis. The axis goes from the North Pole to the South Pole. Earth spins from west to east. That is why the Sun looks like it rises in the east and sets in the west. One full spin takes about 24 hours, which is one day.

What Happens at the Edges

The line between day and night on Earth is called the terminator. It is always moving as Earth spins. At sunrise, your part of the world is turning toward the Sun. At sunset, it is turning away. Near the North and South Poles, day and night can last for weeks or even months at certain times of year.

Fun Facts

• Earth spins at about 1,000 miles per hour at the equator.
• On the Moon, a single day lasts about 29 Earth days.
• A day on Jupiter is only about 10 hours long because it spins very fast.

Did You Know?

If Earth stopped spinning, one side would have constant daylight and extreme heat, while the other side would be in freezing darkness.