Destination Space: Earth
空間距離：地球
Our Home in the Solar System太陽系家園
In our solar system there is only one star.We call this star the Sun.Earth and seven other planets orbit the Sun.
在太陽系中，這裡有隻有一個星球，他就是太陽。地球和其他七個星球繞太陽運行。
Mercury 水星； Venus 金星 Earth地球 Mars火星
Earth is the third planet from the Sun.It is one of the four rocky planets in our solar system.
地球是太陽系第三大星球。也是太陽系四大巖態行星之一。
Earth is the perfect distance from the Sun.This means Earth's temperature is one too hot,or too cold,for life to exist.
地球與太陽的距離適中。這也就意味著地球的溫度是恆定的，不會太熱，也不會太冷，適合生命的存在。
Orbiting and Spinning 公轉與自轉
It takes Earth a whole year to make a complete orbit around the Sun.As the Earth moves around the Sun,it is also spinning on its axis.
地球繞太陽運行一圈的時間是一年。地球在太陽周圍運行的時候，也在自身軌道上自轉。
One full turn or spin, on Earth's axis takes 24 hours.Whithin that 24hours we see the sunrise that begins our day and sunset that begins our night.
Earth is tilted on its axis.This makes diferent areas of Earth closet to or farther from the Sun at different times.This is why we have seasons.
Earth's Layers
Like all the rocky planets,Earth has a rocky outer layer and a metal core.The rocky outer layer is call the crust.
The mantle is between the crust and the outer core.It is mostly solid rock.
Almost three quarters of Earth's surface is covers in water.Without water,there would be no life on earth.
Earth is protected by a layer of gases called the atmosphere.
Earth's temperature,water,and atmosphere make it the perfect place for us to live.
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