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Plan
1. Main parts of the Earth. The difference between them.

2. History of the Earth study.
3. Peculiarities of the Earth’s rotation.

History of the Earth and its parts.

The Earth is made up of air, water, and solid ground. Scientists

call these the atmosphere, hydrosphere, and lithosphere. These terms
come from Greek roots. Atmos means vapor. Hydro means water.
Lithos means stone.

Figure. 2.4. The Atmosphere of the Earth

The Atmosphere. The Earth is surrounded by layers of gases
called the atmosphere. This shields the planet from deadly radiation

and meteors. The atmosphere also acts as a blanket to keep the Earth’s
temperature stable. This blanket is made of 21 percent oxygen, 78
percent nitrogen and 1 percent other gases. It also contains dust and

water vapor.
The Hydropshere. When viewed from space, the Earth might be
called the blue planet. Three-quarters of its surface is covered with

water. This is the hydrosphere. The Earth is the only planet known to
have liquid water. The oceans, lakes, and rivers are filled with plants
and animals. The hydrosphere provides food, fertilizers, and industrial
materials. The oceans produce salt and many other important

chemicals.
The Lithosphere. The lithosphere is the solid part of the Earth. It
has a solid outer mantle about 1,740 miles (2,800 kilometers) thick.

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