Right now, galaxies are merrily churning away, converting nebular gas into stars.

现在，星系正在愉快地旋转着，将星云气体转化为恒星。

A few billion years after the nebular gas runs out the only stars left will be those long-lived red dwarfs.

在星云气体耗尽几十亿年后，剩下的恒星将是那些长寿的红矮星。

Unless the solar wind blew all the nebular particles far away from the planet.

除风把所有的星云粒子都吹到远星球的地方。

In 1873 French scientist, Edouard Roche proposed that the Moon simply formed alongside the Earth out of essentially the same nebular cloud of particles and gasses.

1873年法国科学家爱德华·洛希提出月球只是在地球旁边形成的，本质上是由相同的粒子和气体的星云构成的。

Scientists have had a basic understanding of how the solar system formed since at least 1755, when the philosopher Immanuel Kant proposed the nebular hypothesis.

至少从 1755 年哲学家伊曼纽尔·康德 (Immanuel Kant) 提出星云假说开始，科学家们就对系的形成有了基本的了解。

But, if we trust the nebular model, and believe they evolved out of the same disk as Earth, something must have happened to make them that way.

但是，如果我们相信星云模型， 并相信它们是从与地球相同的圆盘中进化而来的，那么一定是发生了什么事情使它们变成了这样。

The nebular model tells us that, back when Mars was forming, there should have been enough material in Mars's part of the disk for it to grow much larger.

星云模型告诉我们， 在火星形成时，火星圆盘部分应该有足够的物质让它变得更大。