In 1969 when Neil Armstrong said "That's one small step…", he made a lasting impression. On the moon, that is.
1969年阿姆斯特朗的那句"人類一小步。"給人留下了難以磨滅的印象。
Marks on the surface of the moon don't disappear the way marks on the Earth do; a great example is the impact craters we can see dotting the moon's surface.
月球表面的記號不會像地球那樣輕易地消失。最典型的例子就是我們肉眼可見的月球表面散布的隕石坑。
Many of them are billions of years old!
這些隕石坑中很多有數十億年的歷史。
But Why?
但為什么呢?
If you write your name in the sand at the beach, one day later there's no sign you were there. What's the difference?
如果你用沙子在沙灘上寫下你的名字的話,一天過后,名字就會消失。差別在哪呢?
Here's an experiment you can do to find out. Take two pans and fill them with soil and sand mixed together.
你可以做個實驗來找出這種差別。拿出兩個平底鍋,里面放滿土和沙子并將土和沙子摻在一起。
Now have some young person press her or his hand down into the mixture to make an imprint. One of these surfaces will represent the Earth, and one the moon.
然后找幾個年輕人把手放在沙土中摁出手印。其中一個平底鍋代表地球,另一個代表月球。
Leave your Earth pan outside. Take the moon pan inside and place a cardboard box over the top of it, weighted down with something heavy. Wait a couple days and check again.
把代表地球的平底鍋放在戶外,然后把代表月球的平底鍋放在室內并在它的上面放上一個硬紙盒,再壓上一些重物。幾天過后再進行觀察。
The moon pan will look the same. More than likely, though, the Earth pan won't. Maybe the wind blew the sand around. Maybe it rained or snowed.
你會發現代表月球的平底鍋沒有任何變化。但代表地球的平底鍋卻并非如此,也許是風把沙子吹得到處都是,也許是被雨雪沖刷過。
The point is that Earth has an atmosphere, which results in wind, rain, rivers and streams, lots of motion.
答案就在于地球有一層大氣,大氣可以產生風、雨、河流、小溪等引起運動的事物。
Of course, Earth is also volcanically active: the ground shakes, lava pours out, continents rise and fall.
當然,地球的火山運動是非常活躍的,會造成地震、巖漿噴發、大陸沉降。
By comparison, nothing much ever happens on the moon–except for the impacts that give rise to those craters–even across billions of years.
相比之下,月球在數十億年里基本不會產生這些現象(形成火山坑的撞擊除外)。
So an impression on the moon can be a lasting impression indeed!
因此,你在月球上留下的印記會一直留在那哦!