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Welcome to Planet Earth
Welcome to Planet Earth, the third planet from a star named the Sun. The Earth is shaped like a sphere and composed mostly of rock.
Over 70 percent of the Earth's surface is water. The planet has a relatively thin atmosphere composed mostly of nitrogen and oxygen. Earth has a single large Moon that is about 1/4 of its diameter and, from the planet's surface, is seen to have almost exactly the same angular size as the Sun. With its abundance of liquid water, Earth supports a large variety of life forms, including potentially intelligent species such as dolphinsand humans. Please enjoy your stay on Planet Earth.
[Source: Astronomy Picture of the Day]
