About 4.6 billion years ago, a great swirl¹ of gas and dust some 15 billion miles across accumulated in space where we are now 大约46亿年之前，一股直径约为240亿公里、由气体和尘埃组成的巨大涡流，积储在我们现在所在的空间，

and began to aggregate². 并开始聚积。

Virtually all of it—99.9 percent of the mass of the solar system—went to make the Sun. 实际上，太阳系里的全部物质--99.9％的物质--都被用来形成了太阳。

Out of the floating material that was left over, 在剩下的飘浮物质当中，

two microscopic³ grains floated close enough together to be joined by electrostatic forces. 两颗微粒飘到很近的地方，被静电吸到一起。

This was the moment of conception for our planet. 这是我们的行星孕育的时刻。

All over the inchoate⁴ solar system, the same was happening. 在整个初生的太阳系里，同样的情况正在发生。

Colliding dust grains formed larger and larger clumps⁵. 尘粒互相碰撞，构成越来越大的团块。

Eventually the clumps grew large enough to be called planetesimals. 最后，这些团块大到了一定程度，可以被称做微行星。

As these endlessly bumped and collided, they fractured or split 随着这些微行星无休止地碰撞，它们或破裂，或分解，

or recombined in endless random⁶ permutations, but in every encounter there was a winner, 或在无休止而又随意的置换中重新合并，但每次碰撞都有一个赢家，

and some of the winners grew big enough to dominate the orbit around which they traveled. 有的赢家越来越大，最后主宰了它们运行的轨道。

It all happened remarkably⁷ quickly. 这一切都发生得相当快。

To grow from a tiny cluster of grains to a baby planet some hundreds of miles across is thought to have taken only a few tens of thousands of years. 据认为，从小小的一簇尘粒变成一颗直径为几百公里的幼星，只要花几万年的时间。

In just 200 million years, possibly less, the Earth was essentially⁸ formed, 在不过2亿年的时间里，很可能还不到，地球就基本形成了，

though still molten and subject to constant bombardment from all the debris⁹ that remained floating about. 虽然仍是灼热的，还经常受到仍在到处飘浮的碎片的撞击。