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.
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.
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.
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.