The images of Pluto that the New Horizons probe beamed across 3 billion miles of hard vacuum are, in a word, breathtaking. Towering mountains of ice, smooth plains, a wan alien landscape. They're amazing not only for what they tell us about Pluto, but for instilling wonder at seeing something human beings have until now only imagined and speculated upon.
But did we really see Pluto?
The New Horizons mission wasn't a hoax; human beings really did send a little robot all that way. Just as conspiracy theorists question the Apollo moon landings, some folks claim the Pluto flyby was fabricated. It wasn't. New Horizons spent more than nine years crossing the solar system to glimpse Pluto, which really exists. And it sent back pictures. So that's not what I mean.
What I mean is this: There is something between us and Pluto, aside from the vastness of space. Two sensors called LORRI and Ralph, mounted on New Horizons, are actually "seeing" Pluto. What we're seeing are pictures. And whenever that's the case, we should be deeply, philosophically skeptical about whether what we're seeing has the meaning we're imparting on it.
You might see an image and believe it is "true," but it isn't necessarily the truth. Every photograph's meaning is limited by the technology that captured it, the technology that disseminated it, and people's ability to understand what it is they're seeing. The nagging question Is it real? plagues not just science, but philosophy and the arts as well. We can barely trust our eyes and brains.
Technology only makes the problem worse.
Scientists don't spend a lot of time worrying about this sort of stuff. They don't have the bandwidth. It requires a lot of concentration to send something the size of a piano across the solar system to peek at something so far away it takes 248 years to orbit the sun. It also requires almost 15 years and $700 million. Those are not numbers that lend themselves to existential musing.
The photos are composites of multiple images taken by three sophisticated cameras aboard New Horizons. Alice is an ultraviolet imaging spectrometer. The Long Range Reconnaissance Imager (LORRI) is essentially a black-and-white digital camera with a telephoto lens sporting an 8.2-inch aperture. Ralph features three black-and-white and four color imagers; it is the probe's primary "eye" and the reason you're seeing such vivid color. It offers resolution 10 times that of the human eye. As far as NASA's concerned, what you see here is what you'd see if you were out there.
"These early-release pictures from New Horizons are pretty much true color," says Paul Geithner, the James Webb Space Telescope’s deputy project manager for technical issues. "So it would look like that if you were in an airplane out there close by."
While that may be true, the fact no one's ever seen Pluto with the naked eye does throw a philosophical wrench into the idea of “seeing” it. We can’t actually visit Pluto, so we sent a probe. We trust a conduit because it’s our only option, but the technology doesn’t see around all corners. And, most of the time, scientists aren’t any more sure of what’s out there than the rest of us.
Pillars of Creation is a perfect example. That's the awe-inspiring image of three unfathomably enormous columns of cold gas in the Eagle Nebula some 7,000 light years from Earth. The Hubble Space Telescope made the photo in 1995. Last year, NASA aimed Hubble at the nebula again, hoping to capture an even more incredible view in near-infrared light (which humans can’t see) as well as visible light. But it's possible the pillars aren't even there anymore. It's possible they weren't there 20 years ago, either. (If they do still exist, a study shows they are deteriorating .) The Hubble pulled in old light, traveling almost incomprehensible distances across the universe to its lens. The photo is essentially a memento mori. But that is always true. A camera captures proof of a single moment, no more.
The moments before and after that moment remain unclear.
—Susan Sontag, On Photography.
Sontag was a writer and filmmaker. The book she wrote in 1977 remains a pillar of contemporary thought on photography and the fallibility of what it creates. A photo “passes” for proof of an object or event, but it can never be considered absolute truth.
It’s not hard for a photographer to understand why you'd question actually seeing Pluto—the same question has nagged photographers since Nicéphore Niépce made View from the Window at Le Gras in 1826. A camera is a simple machine: A lens and a shutter that allows the passage of light, which hits the chemical emulsion of film or the pixels of a digital sensor. That intervening technology takes photons bouncing off an object and interpolates them into data. More technology turns that data into an image. And still more technology disseminates that image so you might see it.
"The moment you stick something between you and an object, you’re no longer seeing it the way it is," says Phil Plait, astrophotographer and writer of Slate's Bad Astronomy blog. "Our eyes are very easily fooled by perspective and optical illusions. Our brain has to interpret what our eyes are doing. You’re not seeing the way the world really is under any circumstances."
From an iPhone mounted on a selfie stick to a telescope pointed deep into the cosmos, making a picture is a series of decisions—focus, distance, exposure, contrast—made by the person (or probe) firing the shutter. That's why a photo cannot exist as infallible evidence. A camera is opinionated. Someone chooses where to point it, how to shoot it, and how to process the image it creates. You don't see what the camera saw, only what it produced. Send a machine 3 billion miles away and the gap gets even bigger.
"One can’t possess reality,” Sontag wrote. “One can possess (and be possessed by) images.” A photo of Pluto is not Pluto any more than René Magritte's painting of a pipe was a pipe. A photo is a representation, a conduit for the real thing, one that is both fallible and changeable.
These issues aren't new. In the early 1600s, when Galileo first spied Jupiter's four moons through his telescope, scholars scoffed at the idea he was seeing anything at all. Antony van Leeuwenhoek had the same experience describing what he saw through his microscope. How could an instrument reveal what couldn’t be seen with the naked eye? How can you be certain that what you’re capturing through a new technology is real?
Do you even know what you're looking at?
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The historian and philosopher of science Douglas Allchin has spent his career pondering such questions. "On imagery from Pluto, it is simply refreshing to be reminded of how indirect 'seeing' is," he says. "We have quite a degree of confidence in creating a semblance of the original. But it is all quite indirect, mediated by technology."
Philosopher Ian Hacking tried to help the scientists get their heads around this in his 1981 article "Do We See Through a Microscope." He argued that it is difficult to know just what you're seeing when something is viewed through technology. Whether peering through the first microscope or pondering a photo of Pluto, people rely upon something philosophers call a “vicarious selector,” a way of seeing that Allchin describes as an "indirect, or secondary—but not necessarily unreliable—means of probing phenomena that are otherwise difficult to observe."
In the case of the microscope, Hacking’s solution to the problem is interference—interacting with what you're studying in a physical way to see if it responds in a manner that can be seen in the image. “We are convinced about the structures we seem to see because we can interfere with them in quite physical ways, say by microinjecting. We are convinced because instruments using entirely different physical principles lead us to observe pretty much the same structures in the same specimen,” he wrote.
While these findings can aid in understanding, it isn't really possible, or at least feasible, to interfere with a celestial body at the far end of the solar system. But in the case of Pluto, if the data collected by New Horizons corresponds with what's seen in the pictures, that will provide scientists with some evidence that the pictures are more than pretty.
Scientists will pore over the data and images for decades. They're driven by inquisitiveness, the "Why" of something. The rest of us are driven by wonder, the "How" of something. Mankind has always looked at the sky with wonder, and these images feed that primal instinct and imbue in us a universal sense of discovery.
"Nintey-nine percent of the people who see [photos of space] have no idea what these things are, but it doesn’t matter because they are so beautiful they like them anyway," says Jon Lomberg, an artist who, among other things, collaborated with Carl Sagan and designed the Golden Record now roaming interstellar space aboard Voyager 1. "It seems to touch something inside ourselves—the word spiritual might be getting close to it. The experience of looking at the universe for most people is not technical and dry and scientific."
The wonder goes beyond Pluto to the fact we actually got there. Something we built and hurled into the void crossed the solar system and sent back pictures. In the 54 years since Yuri Gagarin became the first man in space, we've explored the solar system. That is amazing, something to be celebrated.
"You don’t really have to understand a lot about astronomy to know how difficult this is," says Lomberg. "Getting it there, having it work for nine years and having it do exactly what they’re telling it to do. You just want to applaud. It makes everybody think Goddamn! that was a good thing to do!"
So perhaps it doesn't matter that what we saw in those photos may not be real. They are more than data. They are a glimpse of something that, like us, holds a small but significant place in the universe. New Horizons flew by Pluto and we marveled at it, sharing a moment and a feeling that was very real indeed.
