杰瑞在月球上的目标是一个这样的角形反射器
that were left by astronauts from the first Moon walkand later Apollo missions.
是由第一个在月球行走的宇航员 以及后来的阿波罗计划安置的
It takes just 2.5 seconds for the light to return to Earth.
激光只需2.5秒就返回地球
Jerry has measured this figure every day for decades.
杰瑞已经测量了数十年时间
And his results reveal something remarkable.
而他的数据清楚的显示
The Moon is receding 3.8 centimetres per year,
月球每年远离地球3.8厘米
which kind of surprised me, I didn't really give it a thought
真的很奇怪我从没想过会这样
whether it was standing still or moving, but it is, it's moving away.
它并不是静止或者移动它正在远离
And eventually, we'll lose it.So the Moon will not be with us forever.
总有一天，我们会失去月球 所以月球不会永远和我们在一起
Eventually, it will drift away into space and Earth will lose its climatic stability.
最后，它会漂流到太空里 地球会失去它的稳定气候
But there's no need to panic.It'll take billions of years.
但是没有必要恐慌 这个过程将花费数亿年
Earth's chance collision with its twin was perhaps the critical moment in its history.
地球和它的孪生星球撞击 也许是地球历史上最关键的时刻
By this theory, it ensured that the planet held on to its protective atmosphere.
它使得地球可以留住保护自己的大气层 它使得地球可以留住保护自己的大气层
