Lĕssøn 2

! The Planets are the very large round objects in space
       that move around the Sun.
                  ! There are nine planets


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Mercury

Venus

Earth

Mars

　

me 　 Mercury is the closest planet to the sun. Its mean distance from the sun is approximately 58 million km; its diameter is 4875 km; its volume and mass are about 1/18 that of the earth. Mercury revolves about the sun in a period of 88 days. Radar observations of the planet show that its period of rotation is 58.7 days. Because its surface consists of rough, porous, dark-colored rock,Mercury is a poor reflector of sunlight.

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	v Venus is the second planet in distance from the sun. A great amount of the Sun's heat is trapped by its atmosphere. This makes it hotter than Mercury. Venus doesn't have any satellites. it is closer to the Earth Than any other planets. Venus can be seen as a star and is sometimes called "The Evening Star".
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e 　 Earth is the third planet from the sun and the fifth largest in the Solar System. The mean distance of the earth from the sun is 149,503,000 km. Earth has sunlight, water and gases. It is the only planet known to support life.
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	m Mars is astronomy, fourth planet from the sun in the solar system,named for the Roman god of war. it is the third in order of increasing mass. Almost all its water is frozen into ice. Mars is made of rocks that have lots of iron. The iron in the rocks and soil makes the planet look red.
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