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|Earth: The Water Planet|
|Seventy percent of the Earth's surface is covered by water. The remaining 30 percent is covered by mountains, volcanoes, deserts, plains, and valleys.|
Earth is the third closest planet to the Sun. It has an atmosphere made up of many different gases, but mainly it is nitrogen and oxygen. The atmosphere gives us air to breathe. We live on the planet Earth.
The Earth orbits around the Sun. It takes one year to go around the Sun one complete time. The Earth also rotates, or spins, on its axis. It takes one day to spin around one complete time. The Earth's axis is not straight up and down, but tilted a little bit. This tilt is responsible for us having seasons. Otherwise, the temperature would be pretty much the same all year long.
What causes the seasons to change on Earth?
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