The background picture is called the Pale Blue Dot. It's kind of a big deal.

For those of you too lazy to click the link (or whose internet connection gave out immediately after loading this page), that picture was taken by the Voyager 1 spacecraft. On November 20, 1980 it left Saturn's orbit and, due to its speed and trajectory, would not encounter Uranus or Neptune on its way out of the solar system. NASA had intended to simply turn the ship outwards and take measurements of solar wind as it turned into interstellar wind (a transition Voyager is measuring now, incidentally), but nerd hero and noted greatest human being ever Carl Sagan, after almost 10 years, convinced them to turn Voyager around and take one last photograph of the Earth. The picture was scientifically useless, as the Earth only shows up as a tiny blueish point, but the sheer insignificance of our planet against the vastness of space is exactly what Sagan wanted to demonstrate. He knew that Voyager was in a position no other probe had ever been in, and possibly never would be, to give us the universe's perspective on ourselves, to show us just how small and fragile we are, despite how important everything seems when you look at it on the ground.

The 10 year delay, though not intended by Sagan, makes the photograph more meaningful in my opinoion for two important reasons. The first is that in 1980 Voyager had just passed Saturn. That's very far away from home, to be sure, but there are still two planets and a Pluto (whatever your stance on that issue) before you get to the edge. In early 1990, when the picture was finally taken, the Voyager probe was well beyond the orbit of Pluto. In 1980, Voyager would have taken a picture of the Earth from "far away." In 1990, it took a picture of the Earth from the edge of our solar system. It wasn't just far away; it had crossed some invisible line that separates some concept of "home" that we still cling to from some concept of "the rest of the universe" that we still hide from. Voyager is the furthest man-made object ever, and will continue to be unless we launch something to catch up to it, and this picture is it looking back from the furthest frontier of human exploration and saying, "That's home. That's where I came from."

The second reason the 10 year delay makes that photograph more meaningful is a more personal one. Voyager 1's mission ended on November 20, 1980. 9 years later to the day, I was born. When Voyager took this picture, sometime between February and June, I was between 3 and 6 months old. I'm in that picture. That's me. When I'm feeling flippant about it, I like to say that this picture is my favorite picture of me, but it's true. I'm among the youngest people alive to be in that picture. Of course, at this vast distance, it doesn't really matter who's in the picture and who's not. It's still a picture representing the whole of human accomplishment as a fraction of a pixel, no matter when it was taken. But the fact that I happen to be in that fraction of a pixel, that I was there, makes me feel somehow more a part of humanity, and makes me feel more at peace. Humans are wonderful and terrible creatures, but looking at this picture keeps me from letting the terrible parts paralyze me, and helps put the wonderful parts in perspective against the infinite wonders of the universe that we can never match.

Aside from the bit about me being a baby in the picture, Carl Sagan said pretty much everything I said, only infinitely more gracefully, so please go read or listen to him. Like I said, he's pretty close to the best human being ever.