評論
打印
The mirrors left on the Moon allow Peter to make a very accurate measurement.
留在月球上的鏡子能讓Peter進行非常精確的測量。
Using a telescope with a built-in laser, Peter can precisely measure the distance from the Earth to the Moon.
利用內置激光的望遠鏡，Peter能夠精確測量地球到月球的距離。
We orient the telescope so that it is facing the Moon.
我們精確定位望遠鏡，使其對準月球。
The laser light, coming out of the telescope, then goes directly up to the Moon.
激光從望遠鏡里射出去，直接射向月球。
It can be reflected by the reflector and it then comes right back through the tube again,
它能夠被反射鏡反射，然后就被重新反射回鏡筒里，
makes its way through the optics and we sense it inside the building.
通過光學的手段，我們在房子里能接收到它。
OK, there it is. Look at that.
啊，在那里。瞧!
There's a really big crater, you can see the shadow in there.
是個很大的彈坑，你可以看到那里有個陰影。
Timing how long it takes the laser beam to go out and bounce back, Peter can precisely calculate the distance to the Moon.
測量出激光射出和反射回所化的時間，Peter可以精確地計算出到達月球的距離。
But trying to hit that tiny mirror, so far away, requires very careful alignment and a bit of perseverance.
但要在如此遠的距離擊中那個細小的鏡子，需要非常仔細的校準，需要一點毅力。
We may send out a thousand million billion photons,
我們發出萬億兆的光子，
whereas coming back... coming back into the telescope might be ten. Ten! Or five, or none!
可能反射回望遠鏡的就只有10個。10個！甚至5個，甚至一個都沒有！
So it is still a very hard experiment because everything has to work just right.
所以這還是個艱難的實驗，因為一切都必須做得恰到好處。
How accurately can you make that measurement, off Neil and Buzz's reflector and back again?
你可以把測量做得有多精確，射向尼爾和巴茲留下的鏡子并反射回？
One to three centimetres. Over a quarter of a million miles.
1到3厘米。超過25萬英里的距離里。
Over a quarter of a million miles out, quarter of a million miles back.
射出去25萬多英里，反射回25萬多英里。
