And how far is that exactly? It's almost beyond imagining. Space, you see, is just enormous—just enormous. Let's imagine, for purposes of edification and entertainment, that we are about to go on a journey by rocketship. We won't go terribly far—just to the edge of our own solar system—but we need to get a fix on how big a place space is and what a small part of it we occupy.
這到底有多遠？幾乎難以想像。你看，空間大得不得了--簡直大得不得了。出于了解和娛樂的目的，我們來想像一下，我們就要乘火箭飛行器進行旅行。我們不會走得太遠--只到我們自己太陽系的邊緣--不過，我們先要明白：空間是個多么大的地方，我們占據的是個多么小的部分。
Now the bad news, I'm afraid, is that we won't be home for supper. Even at the speed of light, it would take seven hours to get to Pluto. But of course we can't travel at anything like that speed. We'll have to go at the speed of a spaceship, and these are rather more lumbering. The best speeds yet achieved by any human object are those of the Voyager 1 and 2 spacecraft, which are now flying away from us at about thirty-five thousand miles an hour.
哎呀，恐怕是壞消息，我們回不了家吃晚飯了。即使以光的速度（每秒30萬公里）前進，也要花7個小時才能到達冥王星。而且，我們當然無法以這種速度進行旅行。我們不得不以宇宙飛船的速度前進。這個速度就很慢了。任何人造物體所能達到的最高速度是"旅行者1號"和"旅行者2號"宇宙飛船的速度，它們現在正以每小時5.6萬公里的速度飛離我們。
The reason the Voyager craft were launched when they were (in August and September 1977) was that Jupiter, Saturn, Uranus, and Neptune were aligned in a way that happens only once every 175 years. This enabled the two Voyagers to use a "gravity assist" technique in which the craft were successively flung from one gassy giant to the next in a kind of cosmic version of "crack the whip." Even so, it took them nine years to reach Uranus and a dozen to cross the orbit of Pluto.
當時（1977年8月和9月）之所以發射"旅行者"號飛船，是因為木星、土星、天王星和海王星排成了一條直線，這種現象每隔175年才發生一次。這就使得兩艘"旅行者"號飛船能夠利用"引力幫助"技術，以一種宇宙甩鞭的形式，被從一顆氣態巨星連續甩到下一顆氣態巨星。即使這樣，它們也要花9年時間才能到達天王星，要花12年時間才能越過冥王星的軌道。
The good news is that if we wait until January 2006 (which is when NASA's New Horizons spacecraft is tentatively scheduled to depart for Pluto) we can take advantage of favorable Jovian positioning, plus some advances in technology, and get there in only a decade or so—though getting home again will take rather longer, I'm afraid. At all events, it's going to be a long trip.
好的消息是，要是我們等到2006年1月（這是美國國家航空和航天局暫定向冥王星發射"新地平線"號宇宙飛船的時間），我們就可以利用有利的木星定位法，加上一些先進的技術，只用10年左右的時間便能抵達那里--雖然再次回到家里恐怕要花上相當長的時間。
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