For me, it's "Pale Blue Dot"
Before Hubble was sending back images from places billions of light years away that looked like abstract art at its finest form, there was this crappy quality digital picture from 1990. It was taken from the Voyager 1 spacecraft, which was released almost 32 years ago, is STILL functioning and still relaying details of the area beyond our solar system and is expected to run until at least 2025. Voyager 1 is and likely will be the most distant man-made object from Earth. Currently, Voyager 1 is 10.22 billion miles from earth (June 19th, 2009).
The photo is from Voyager 1 when it was about 3.7 billion miles away from Earth. On February 14th, 1990 Voyager 1 had completed its primary mission and was ordered to pivot around in order to take pictures of the planets. This was one of the pictures. The streaks are from the reflection of distant sunlight inside the camera. Earth is the small white-ish blue dot inside the orange ring. The name "Pale Blue Dot" came from Carl Sagan he also said:
"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."
It say a lot about what a few billion organisms on a tiny little rock can do. Sending a machine so far away. But if anything, for me, it only re-enforces our insignificance in the universe. I did a lot of thinking when I first saw this picture and it still influences me whenever I see it today.