Earth Is 0.12 of a Pixel in the Last Photos Voyager 1 Ever Took

The dot is twelve-hundredths of one pixel. In a frame of 640,000 pixels, Earth occupies about 0.12 of one of them — less than a point, a smear of pale light too small to resolve into anything at all. It sits inside a band of sunlight, as if posed there on purpose.

That image, taken on February 14, 1990, is one of the most reproduced photographs ever made. It almost never existed. The spacecraft that took it was never supposed to look back, the agency that owned it said no for the better part of a decade, and the picture itself carried nothing a single scientist could use.

The picture no one needed

Voyager 1 was built to look outward — at Jupiter’s storms, at Saturn’s rings — and then to keep going, past the planets, into the dark between stars, until its plutonium ran out and it fell silent. Its two cameras had done their job by 1980. There was nothing ahead worth photographing. The plan was to switch them off and save the power for instruments that could still feel the solar wind thinning out at the edge of the system.

Carl Sagan wanted one more picture first.

Sagan was on the Voyager imaging team, and in 1981, with the Saturn encounters just behind the mission, he began pressing for a picture that had no scientific purpose at all. He wanted the spacecraft, on its way out, to swing its cameras around and photograph the planets it had left behind — a portrait of the solar system shot from the inside, looking home. Earth would be in it. From that distance Earth would be almost nothing, a point with no detail, no continents, no weather. That was the point. He thought people should see it.

Eight years of no

NASA was not enthusiastic. The maneuver had real costs and no return. To aim the cameras back toward the inner solar system meant pointing them dangerously close to the Sun, and the cameras used vidicon tubes — light-sensitive vacuum tubes that could be permanently scarred if too much sunlight fell on them. A picture of Earth as a dot taught planetary science nothing. The spacecraft’s controllers had a long mission to protect and budgets to defend, and a sentimental photograph was an easy thing to say no to.

So they said no, and kept saying it. By NASA’s own accounting it took eight years and six separate requests to get the observation approved; the scientists who lived through it counted a seventh. Sagan was not the only one pushing — Carolyn Porco, who had joined the team in 1983, had landed on the same idea independently and was asking about it from 1985 on — but Sagan was the public weight behind it, and he did not let it die.

Even once the case was won, it could only be cashed at the very end. As long as there were planets ahead — Voyager 2 was still running its own course, reaching Neptune in August 1989 — the program could not spare a spacecraft, a team, or the risk for a photograph with no data in it. Only when the last planetary encounter was behind both probes did the case for the family portrait finally clear.

The window that was closing

And even then it nearly slipped away. NASA was short of money, and the technicians who knew how to write and radio the commands up to a spacecraft so distant that each instruction took more than five hours just to arrive were being laid off or moved to other projects as Voyager wound down. The institutional memory needed to point those cameras was evaporating in real time. It took the NASA administrator himself, Richard Truly, stepping in during the Neptune encounter to make sure the pictures were obtained at all.

The command sequence that survived all this was built by Porco and a JPL scientist named Candy Hansen — every exposure timed, every filter chosen, every slew of the scan platform plotted so the cameras would sweep across the planets without letting raw sunlight fall on a vidicon tube. Even the Sun itself was photographed — through the darkest filter on the wheel, at the shortest exposure the shutter could manage, five thousandths of a second.

On February 14, 1990, the commands ran. Voyager 1 was 3.7 billion miles from the Sun, about forty times farther out than Earth, and roughly thirty-two degrees above the flat plane the planets orbit in — high enough to look down on the whole system at once. It took sixty frames: the wide-angle camera sweeping the scene, the narrow-angle camera zooming in on each world it could find. Venus. Jupiter. Saturn. Uranus. Neptune. And, in one narrow-angle frame, Earth.

Mercury was lost in the Sun’s glare. Mars turned only a thin crescent toward the spacecraft, and what little of it there was drowned in sunlight scattering around inside the camera. Pluto was too faint and too far. But the cameras caught six planets and the Sun, the only portrait of its kind ever made — the solar system seen from beyond its planets, by something that came from it.

About thirty-four minutes after it photographed Earth, Voyager 1’s cameras were commanded off for good. They have never been turned on again.

A point of light, by accident

The data came back slowly. The frames sat on the spacecraft’s tape recorder while Magellan and Galileo took priority on the Deep Space Network’s antennas; it was March before Voyager 1 began playing them down, and the last of the image data did not reach Earth until May 1, 1990. When the Earth frame was assembled, the planet was the dot already described — about 0.12 of a single pixel, twelve-hundredths of one of the 640,000 pixels in the frame.

The band of sunlight it sat in was not real. It was an artifact — sunlight scattering off the camera’s optics and sunshade, throwing streaks of light across the picture. By pure chance, one of those scattered rays fell across the spot where Earth happened to be. Everything that has ever happened to our species was, in that image, a fleck suspended in a stray reflection inside a camera lens.

The sentence that outlived the photograph

Four years later, in his 1994 book Pale Blue Dot, Sagan wrote the passage the image is now inseparable from. Looking at the dot, he listed what it held:

“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 photograph he had argued for across eight years and a half-dozen refusals turned out to carry nothing the instruments wanted. No spectra, no measurements, nothing a planetary scientist could publish. What it carried instead was the one thing none of the other Voyager images could: a view of ourselves small enough to be honest.