what+we+know



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The Earth has one moon, and it’s the third planet from the sun. The planet has a twenty-four hour rotation time. It rotates three hundred and sixty-five and a quarter times during each complete revolution around the sun. =====



The first map of the whole earth was created in 1689. It looked something like the map on the right. Obviously, there are a lot of errors on it. It wasn't until the 1950s and 1960s that human beings took the first pictures of the earth from space. Before that, no human had ever been far enough away from the earth to take a picture like the one on the left. That picture was taken by the astronauts on board the Apollo 8 mission.

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Because the axis is tilted 23.5 degrees, earth is cold at the top and bottom and warm in the middle. The earth's shape is an oblate spheroid. This planet's surface has many different kinds of terrain including tropical islands, grassy plains, forests, dry deserts, mountains that can be up to 13,796 feet high [|(http://geology.com,]) vast oceans that can be as deep as 7 miles (Mariana Trench in the Pacific Ocean), and the ice-covered lands in both tips of planets. =====

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It is a very populated planet with hundreds of different species inhabiting it. There is a dominant species on it called humans. They’re the most intelligent animals inhabiting this planet. Accompanying this species are a large ranges of animals, insects, reptiles, fish, and birds that coexist on this very lively planet. =====

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Inside, the earth has a solid inner core, molten outer core, a thick partially molten mantle, and a thin crust. All of the layers are rich in metals, making earth the most dense planet in our solar system. =====

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