大约7亿年前 地球开始降温。
It was the beginning of an Ice Age.
是一次冰河时代的发端
No one is quire sure why it happened,
没人能确定发生原因，
but it seems that our entire word was plungedces into an interminable winter.
冰从地球两极不断蔓延 直至将整个世界拖入一个漫长的冰封冬季。
Some scientists have called it the time of snowball Earth.
某些科学家称这段时期为“雪球地球”
because the whole planet would appear as an icy ball.
因为当时整个行星 看起来就是一个冰球。
Others believe that the Earth was cold but not completely frozen.
其他一些人认为地球是冷的 但是并没有完全冰冻
Traveler to Jupiter and you can get some idea of what Earth might have looked like.
去木星看看 您对地球当时可能的模样就有些概念
Europa is one of Jupiter's moons.A frozen landscape
欧罗巴是木星卫星之一
that might mirror parts of Earth millions of years ago.
冰冻现象可能是地球 数百万年前的一面镜子
but knowing what earth look like
仅仅知道地球的模样
doesn't convey just how terrible the conditions would have been.
并不能准确体会到当时的情况
A blizzard, high in the Alps, in mid-winter, is as close as I can get.
冬季阿尔卑斯高处的暴风雪 是我能接触到的与当时最接近的情况
