地球的诞生大约46亿年前,在发光的太阳四周包围着圆盘状的气体和微尘。这个气体和微尘层不久即分裂,产生10兆个左右的小行星。其中便有一个是地球,我们的地球母亲便这样诞生了。当时在地球的轨道附近大约存在着100亿个直径约10公里,重量约1兆吨的小行星。小行星不断撞击且合为一体而逐渐成长,在体积达到一定程度时便加速成长,随着重力增加,吸引更多的小行星,也吸引了那些飞散的碎片。当时的地球,体积只有目前的一半,平均一年内会受到1000个以上小行星的撞击。撞击地球的小行星含有大量的金属铁和岩石成份,在后来,类似目前的彗星而由冰构成的小行星也撞击到地球上,这些小行星上含有碳、氢、氮、氧等生命的材料物质。小行星以每秒数公里到十几公里的惊人速度撞击 About 4.6 billion years ago, the birth of the earth surrounded the disc-shaped gas and dust around the glowing sun. The gas and dust layer soon split, resulting in about 10 trillion asteroids. One of them is Earth, so our Mother Earth is born. At that time, there were about 10 billion asteroids with a diameter of about 10 kilometers and a weight of about 1 trillion near the Earth’s orbit. Asteroids continue to hit and combine to grow and grow as the volume reaches a certain level, then accelerate the growth. With the increase of gravity, attracting more asteroids also attract those flying fragments. At that time, the earth had only half the size of the current one and hit an average of more than 1,000 asteroids a year. Asteroids that hit the Earth contained a large amount of metallic iron and rock components. Later, asteroids like ice and other comets, which collided with Earth, also contained materials of life such as carbon, hydrogen, nitrogen and oxygen substance. Asteroids strike at an astonishing speed of several kilometers per second to a dozen kilometers