The Power of the Sun

The Power of the Sun

Each day, there is some sunlight and some darkness. During the day, the sun looks as if it is moving across the sky from east to west. But the sun is a huge star that doesn't move at all. So why does the sun look like it creeps across the sky from morning until night?

Earth is constantly spinning on its axis. Earth's axis is an imaginary line that passes through the North and South Poles. Think of a marshmallow on a roasting stick. The stick that you poke through the center of the marshmallow is like Earth's axis. It takes 24 hours, or one day, for Earth to complete a full turn on its axis.

At dawn, or in the morning, the sun rises in the east. But the sun's rays are always shining on Earth. They shine on only half the planet at a time. The side of Earth facing the sun has daytime. The side of Earth facing away from the sun has nighttime. During the day, Earth is facing the sun's light. The sun provides light and warmth. At dusk, or nightfall, Earth faces away from the sun's light. It becomes darker and cooler.

Although the sun appears to move across the sky, it is not moving. Earth is constantly spinning on its axis.

Each day has the same number of hours. However, all days do not have equal amounts of daylight. Summer days have more hours of daylight than winter days have. This is because Earth's axis does not run straight up and down. It tilts at an angle. During the summer months, the Northern Hemisphere tilts toward the sun. The opposite is true in the winter months.

The Northern Hemisphere tilts away from the sun. The hours of day and night are about the same in spring and fall.

The United States is in the Northern Hemisphere. When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere.