向外星人介绍地球的英语作文作业帮

太阳系八大行星之一,地球自西向东自转,同时又围绕太阳公转.地球自转与公转运动的结合使其产生了地球上的昼夜交替和四季变化地球自转和公转的速度是不均匀的.同时,由于受到太阳、月球、和附近行星的引力作用以及地球大气、海洋和地球内部物质的等各种因素的影响,地球自转轴在空间和地球本体内的方向都要产生变化.地球自转产生的惯性离心力使得球形的地球由两极向赤道逐渐膨胀,成为目前的略扁的旋转椭球体,极半径比赤道半径短约21千米. 阿地球是由一系列的同心层组成.地球内部有核（地核）、幔（地幔）、壳（地壳）结构.地球外部有水圈和大气圈,还有磁层,形成了围绕固态地球的美丽外套. 地球作为一个行星,远在56亿年以前产生于原始太阳星云. One of the eight planets of the solar system,the earth rotation from the west to the east,and orbit the sun.The earth rotation and the combination of the revolution movement so as to produce a day and night on earth and seasons change the earth rotation and the speed of the revolution is not uniform.At the same time,because of the sun,the moon,and by nearby planets gravity and the earths atmosphere,ocean and earths internal material factors,the earth spin axis in space and the direction of the earth in the body to produce change.The earth rotation inertia centrifugal force produced by the poles of the earth makes spherical gradually expand to the equator,become the current slightly flat spin ellipsoid body,extremely radius than the equator short radius about 21 km. O earth consists of a series of concentric layers.The interior of the earth have nuclear core,curtain mantle,shell crust structure.The earths outer have hydrosphere and atmosphere,and magnetic layer,formed around of the solid earth beautiful coat. The earth as a planet,far before 5.6 billion years produced in the primitive solar nebula.