The Earth Case

When you look at the Earth you see green and blue. The green is the land and the blue is the water. The water covers more than seventy percent (70%) of the Earth. And the land covers less than thirty percent (30%) of the world. As astronaut Charles Walker said, "My first view - a panorama of brilliant deep blue ocean, shot with shades of green and gray and white - was of atolls and clouds. Close to the window I could see that this Pacific scene in motion was rimmed by the great curved limb of the Earth."

The Earth is made up of three layers. First is the core made up of nickel and iron in the very middle of the Earth. The second layer is called the mantle and that is made of silicon, iron, and oxygen. The last layer is the one that we live on. It is called the crust and is made of oxygen, iron, silicone, and magnesium. Sixty-five percent (65%) of the Earth's mass is made up of oxygen and iron.

The Earth also has gravity and magnetic force fields. Gravity is the force that pulls everything toward the center of the Earth. The Earth's orbit makes the seasons. Without our orbit the earth would be very hot or very cold. The highest temperature ever recorded on the earth is 135 degrees and the coldest temperature ever recorded was -150 degrees.

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