In the spring of 1990, Voyager 1 had become the most distant man-made object in the solar system. At the urging of the famous astronomer Carl Sagan, NASA directed Voyager to take a series of photographs of the planets between February 14 and June 6, creating the first 'family portrait' of the solar system. These were the last pictures ever taken by the probe before its camera equipment was shut off to conserve power. One of these pictures was of Earth, a picture which in its own way has become as iconic as The Blue Marble and Earthrise. It was taken at a distance of 3.7 billion miles—more than 40 times the distance from the Earth to the Sun—and shows the Earth as a small speck in the grainy image.

Sagan was so inspired by the image that he titled the second to last book before his death Pale Blue Dot: A Vision of the Human Future in Space. In his own fashion, Sagan was an optimistic nihilist, a humanist that had a vision of man that both encompassed our greatest triumphs and our lowest failings. The introduction to his book is a sobering reminder that remarkably manages to both show how insignificant the Earth is while at the same time emphasizing the consequences of our own actions:

"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known."