It’s hard to overstate the impact of the moment a human being set foot on another celestial body. The man who did it, Neil Armstrong, has died: http://www.space.com/17308-neil-armstrong-photo-legacy-rare-views.html
If our species survives the next thousand years – by no means a given – settlement of the solar system seems likely, although not certain. Presuming that is our future, few human beings will be remembered more than Armstrong, the astronaut who first walked on the moon, back in 1969.
Those with little interest in history may not appreciate the incredible journey our culture has been on, and the culmination of that journey represented by that one act: It was less than five hundred years ago, Galileo ran afoul of the Pope for championing the heliocentric view that the Earth and other planets revolved around the sun: http://en.wikipedia.org/wiki/Galileo (a view that was not discovered by Galileo, but developed by Copernicus, although he was not the first to imagine the possibility, either).
The 16th century may seem like a long time ago, but by the scale of human history, never mind geologic history, it’s a relatively short period. From a universe composed of us and the earth beneath our feet, to a universe in which human beings can travel 384,400 kilometres across the vacuum of something called space to land on another giant moving object; automated robots can land on other planets and explore them; space probes can travel to the outer edges of the solar system – so far that our own sun is just a very bright star – en route to interstellar space; and telescopes stationed in orbit can peer to the very edges of the known universe, as well as identifying other planets around distant stars.
It’s a gut thing. It either resonates with you or it doesn’t. I fall into the first category. Settlers on Mars are still on the distant edge of possible reality, and human expeditions to the outer edges of the solar system are likely at least a century away. But kids born today, with the right combination of smarts, luck, hard work and/or wealth, stand a good chance of having the opportunity to fly in near-Earth orbit and perhaps beyond. My guess is a trip to orbit for those adults will be about as exotic as a trip to the Galapagos is for us today: most of us won’t do it, true, but the wealthy can easily, and even some with more modest incomes can if they make it a top priority.
The sky’s no longer the limit, and Armstrong is one of the reasons why.