Final accumulation of planetarysized objects is generally believed to come from the gravitational relaxation of the disk of planetesimals . 行星大小的天体的最终积累成功，一般认为归因于星子圆盘的引力弛缓。
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During accretion , the kinetic energy of the colliding planetesimals was converted into thermal energy , so the earth grew extremely hot as it came together 在增生阶段，小行星体的碰撞动能转化成了热能，因此当它聚集到一块时地球变得非常热。
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They may have been a source of part of the atmosphere of the terrestrial planets , and they are believed to have been the planetesimal - like building blocks for some of the outer planets and their satellites 它们可能是陆地行星大气的部分来源，他们也被认为是一些外层行星及其卫星的像星子一样的构成石块。
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They may have been a source of part of the atmosphere of the terrestrial planets , and they are believed to have been the planetesimal - like building blocks for some of the outer planets and their satellites 他们本来可能是地球行星大气层的来源之一，而目前的说法一直是他们是类星子堆积块，由一些外部行星和他们的卫星所造成。
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When the solar system was newly formed , the huge gravity of jupiter pulled planetesimals away from the sun , indirectly putting the earth under a collision barrage of objects of various sizes during the first hundred millions of years after the formation of the earth . hese violent impacts increase the amount of basic elements of life , water and organic compounds , on earth 在太阳系形成之初，木星巨大的重力把组成行星的物质牵引离开太阳，间接令地球在它形成后的最初数亿年间，饱受不同大小的物体撞击，这些猛烈的撞击为地球增添了不少构成生命的重要元素水和其它有机化合物。
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Models of the solar system ' s early history posit that the frequency of impacts should have tapered off between 4 . 5 billion and four billion years ago because most of the planetesimals ? the small rocky bodies that formed from the solar nebula ? were gradually cast out of the inner solar system or absorbed by the outer planets 描述太阳系早期历史的模式假设，撞击频率应该在45 ~ 40亿年前趋缓，因为大部份的微行星（由太阳星云形成的小型石质天体）逐渐被驱逐出内太阳系或被外行星吸收。
