现如今，这种乌托邦空想已经过时了，我们对所面临的威胁有了更深刻的认识，从彗星撞击到流行感冒，再到气候变化。

Now utopia has grown unfashionable, as we have gained a deeper appreciation of the range of threats facing us, from asteroid strike to epidemic flu and to climate change.

youdao

在地球的最初岁月中，它曾被成千上万个这样的彗星撞击。

In Earth's formative years, it was hit by thousands of comets like this.

youdao

现在主流的学者认为，地球上的水来自彗星撞击后的沉淀物。

Until rather recently, the prevailing wisdom has been that Earth's water supply was primarily deposited by comets.

youdao