The path Earth takes on this long journey is called its orbit . One orbit around the Sun is known as a revolution. The Earth travels around the Sun at 66,663 miles an hour. The Earth could not be our home if it had a different kind of atmosphere. The layers of gas that surround Earth protect us from dangerous space radiation.
White sunlight contains a prism, or rainbow, of colors.
When sunlight hits the atmosphere, some of its blue color is separated. This is what we see when we look up at the sky. Our atmosphere blanket is not very thick. The air that surrounds the Earth is made up mainly of nitrogen and oxygen. Scientists have divided the atmosphere into several different layers.