关于地球、宇宙、恒星的知识要英文。
地球的 The earth is from inside to outside our solar system, but also the third planet in the solar system, quality and density biggest diameter of earth-like planets. It also is often called the world. A word of English Earth Earth from Old English and Germanic. Earth has 44 ~ 46 billion years old, and have a single natural satellite the moon with 30 days surrounding earth, and the earth the cycle of rotating the cycle of nearly 24 hours in one year cycle rotation and revolution around the sun. Disney set the documentary.
