On Valentine’s Day in 1990, more than four billion miles from earth, in the vast emptiness and silence of space, the camera shutter of the spacecraft Voyager 1 snapped rapidly, taking sixty frames of photographs in quick succession. Among them was an image that has become one of the most famous pictures ever taken from space. In it, the earth is but a tiny speck, caught amid scattered rays of sunlight.
It was Carl Sagan who suggested that Voyager 1 take a look back and photograph the earth as the probe hurtled on its quest into deep space, beyond our solar system, where it remains today. Inspired by this image, Sagan mused in his book Pale Blue Dot: A Vision of the Human Future in Space (1994): “Look again at that dot. That’s here. That’s home. That’s us.” He ended by saying, “Every saint and sinner in the history of our species lived there—on a mote of dust suspended in a sunbeam.”
Sagan’s lyricism was intended to foster a timeless connection between all past and present inhabitants on earth. Masterful in his use of astronomical imagery to engage the public with science, he is best known for his thirteen-part television series Cosmos, which was first broadcast on PBS in 1980. It has since been viewed by over 500 million people in sixty countries. Many generations of scientists since then were brought to science by Cosmos.
The widely publicized image of the earth as a pale blue dot floating in space began a revolution in the perception of our planet. Photographic images of the night sky taken from the earth and satellite images taken from space, looking back at earth as well as looking outward into the solar system and beyond, continue to be an important source of the public’s knowledge about the cosmos. Consider, for example, the first photographic images of the full earth taken by the lunar orbiter in 1966, the famous image of the Horsehead Nebula taken from the Anglo-Australian Observatory by the astrophotographer David Malin, and Michael Benson’s images—some manipulated by computers—made from photographs taken from space probes in his book Beyond, which have provided stunning visual evidence of our place in the solar system and shaped our notions of space.
Both Benson’s Cosmigraphics: Picturing Space Through Time and the astronaut Chris Hadfield’s You Are Here: Around the World in 92 Minutes continue Sagan’s legacy of using the visual image to evoke the realities of space and science for a larger audience. In an age when so many of NASA’s images are available online, and when space exploration by probes like Rosetta is so focused on the possibilities of colonization and the potential extraction of resources from comets, these books also raise a larger question. Beyond generating awe and wonder, what scientific purposes do astronomical images serve?
The night sky has been documented and studied for thousands of years. The hammered copper and gold Nebra Sky Disk, dating to 1600 BC and found in the Saxony-Anhalt region of Germany, depicts the sun, lunar crescent, and stars, including a cluster believed to be the Pleiades. The ancient Mesopotamians were also assiduous and prolific astronomical recorders. The inscriptions on the Babylonian Venus Tablet, which dates to 700 BC and marks the position of the planet Venus in the sky, suggest that the Babylonians, like all ancient peoples, saw a direct connection between celestial and terrestrial phenomena: whether or not they could see Venus in the sky determined whether or not it rained on earth.
It was clear to them that these apparent correlations required an explanation, an agent who ensured that they recurred, and for this they turned to their gods and, occasionally, a demiurge. Put another way, the first explanations for observed celestial phenomena, what we could characterize broadly as cosmological theories, were in fact myths. These myths in turn led to representations and images. One way of understanding the role of images in modern astronomy is to consider astronomers, like their ancient precursors but now equipped with telescopes, as cosmological mapmakers and documentarians.
Astronomy, perhaps more than any other discipline, is a science that relies on images. Unlike other branches of science, no controlled experiments can be performed on the heavens. Therefore, observations are the closest that astronomy gets to actual experiments. For example, the Sloan Digital Sky Survey, operational in New Mexico from 2000 to 2011, has created a picture of about one third of the entire sky. Several large ground-based telescopes currently under construction, including the American-led Large Synoptic Survey Telescope in El Peñón, Chile (LSST), the Thirty-Meter Telescope in Mauna Kea, Hawaii (TMT), the Giant Magellan Telescope at the Las Capanas Observatory in Chile (GMT), and the European Extremely Large Telescope at the European Southern Observatory (ELT), also in northern Chile, will document much more of the sky, capturing extremely faint objects and providing three-dimensional maps of the universe with unprecedented depth and detail. Chile is often chosen because of the clarity of the sky in its northern desert.
The amount of data that these future surveys will generate is staggeringly large. The camera on the LSST, for instance, will generate terabytes of data every single night. That is the amount of information in a thousand sets of the Encyclopedia Britannica. Visualization is even more important in the age of Big Data as we try to comprehend the complexity that results as we extend our reach farther in the sky.
Celestial representations and maps chart how the human view of the heavens shifted from the imagined and fantastical to the reasoned. The impetus for this shift was quite simple: navigation. Our ability to make increasingly sophisticated maps was driven by a seemingly inherent desire to explore our own planet. But to explore the earth and navigate the seas, we needed to look up at the heavens to see the stars as a compass. So terrestrial maps don’t just map the known world of terra firma. They also map the heavens and are clues to the earliest understandings of the universe.
Benson’s Cosmigraphics captures this shift by assembling a compendium of artfully curated images that present “a visual record of our attempts to visualize the universe and our place within it.” Benson has sifted through archive after archive of images, focusing on representations of the cosmos rendered by hand, and excluding straight photographs. There are manuscript drawings on vellum, all forms of prints, from engravings to etchings to woodcuts and offset prints, as well as computer- generated graphics, some based on supercomputer simulations of astronomical phenomena. Benson has collated images that range from premodern cosmogony to modern cosmology.
He is not concerned with the scientific accuracy of these images, although some of them were considered accurate at the time and place in which they were made. This is why, he tells us, he has included images such as medieval illustrations of Dante’s Paradise that fall well outside the category of what would be considered traditional astronomical images. In pictures such as Andreas Cellarius’s 1716 map of Tycho Brahe’s modified geocentric model, aesthetics outweigh scientific accuracy as Benson’s criteria for picking images. The image illustrates Brahe’s alternative to the Copernican model, in which all the planets—except for the earth—orbit the sun, and the sun in turn orbits the earth with all its planets in tow. Yet he says he is searching for some “historical or cultural truths” in them. The subject of his book is thus “enigmatic” images that chart our historical journey as we search for our place in the universe. Before the 1600s, astronomers were often astrologers, Renaissance painters were just as ardent students of optics as were scientists, and many scientists developed a lexicon of illustrative styles to document their observations through a telescope or a microscope.
Astronomers have often used images to reveal the intricacies of science to the larger public, which is also what Benson’s Cosmigraphics does. Cosmology appears in Cosmigraphics to have evolved seamlessly and without intellectual conflicts and ruptures. As a result, his compendium does something surreptitiously: it also persuades the reader of the provisionality of science without generating a sense of instability. The trial of Galileo over his interpretation of the solar system is not mentioned.
The reader gets the impression that the story of cosmology, rather than being contingent and chaotic, is a visual narrative of smooth progress and growing refinement in the quest for understanding our place in the universe. Benson’s presentation softens the disorienting shock that often accompanies what are in effect radical changes in conception or understanding. For example, Robert Fludd’s 1617 account of the formation of a geocentric cosmos that originates with light contrasts with Hartmann Schedel’s model in his Liber chronicarum (1493) that starts ab initio with earth and water, consistent with the account of biblical creation.
Unlike Benson, Hadfield presents photographic images of the earth from the International Space Station (ISS). His planetary photographic tour is a visual delight and offers a unique perspective and window on our planet. His photographs chronicle not only visible nature’s wonders but the consequence of human alterations to the face of the planet. Culled from 45,000 photographs that he took during his five-month sojourn on the ISS, Hadfield’s goal is to help the public appreciate the beauty and variety of our planet.
He succeeds. Hadfield’s photography is the space counterpoint to Ferdinand Magellan’s 1519 circumnavigation of the earth, the voyage that first transformed our view of the planet. For Hadfield, these photographs provide
a new perspective; we are small, so much smaller even than we may have thought. To me that’s not a frightening idea. It’s a helpful corrective to the frantic self-importance we are prone to as a species—and also a reminder to make the most of our moment on this beautiful, strange, durable yet fragile planet.
Many of the photographs have an otherworldly feel to them—particularly striking is one of Iran’s largest desert, Dasht-e Kavir, which is covered with salt flats left behind from an ancient ocean that dried up, leaving a pattern akin to Jupiter’s giant red spot. Then there is the huge indentation in the landscape of Mauritania called the Richat Structure and known as the Eye of the Sahara to astronauts, who frequently use it to orient and locate themselves.
In a recent interview with Dan Schwabel of Forbes, Hadfield commented that the view from the ISS makes the rising specter of climate change more palpable and urgent. For example, drastic changes to the planet over even the timescale of twenty-five years have become visible—as with the drying up of the Aral Sea, which is partly in Kazakhstan and partly in Uzbekistan. Through these photographs, Hadfield has become an unlikely and strong ally in making the case that human activity is causing climate change.
As these books show, imagination, representation, and documentation all have a part to play in visualizing science. Spectacular images have prompted scientific inquiry and have generated scientific questions worth asking. And it is on this issue that Benson makes his boldest and somewhat far-fetched claim—that images generate new discoveries. This is contrary to how most scientists conceive the origins of breakthroughs. However, Benson’s book reminds us that oftentimes celestial phenomena were imagined before they were observed and documented.
Two examples illustrate this well. In 1584, Giordano Bruno imagined other planets in his book De l’infinito, universo e mondi (On the Infinite Universe and Worlds), a phenomenon that is now being documented by NASA’s Kepler Mission, which recently discovered several thousand planets outside our solar system. The Kepler Orrery, which shows a model of these planets and their systems, is included in Cosmigraphics. Second, the debates on life and water on Mars began in the nineteenth century with telescopic views by the astronomer Percival Lowell, depicted in drawings that Benson has also included. Inspired after reading a book by the astronomers Camille Flammarion and Giovanni Schiaparelli, who claimed the existence of a network of canals on the Martian surface, Lowell interpreted his observations as indications of the presence of water, and therefore intelligent life.
NASA’s Mars missions were not designed with Lowell in mind, yet the question he raised was finally settled scientifically when the rover Curiosity landed on the red planet on August 6, 2012. Drilling into an old Martian rock, instruments aboard Curiosity found both evidence for ancient water on Mars that has now dried up and the simple organic molecule methane, but no life. What Lowell’s drawings did was to generate the question and deem it interesting. So images can propel us from the imagined to pursue and endeavor to construct what Benson calls “maps based on actual information.”
Benson makes the case that his curated images are science and art—that is, they are scientific arguments in visual form, although they are not always entirely accurate, and yet simultaneously they are also art. Here he borrows generously from the architectural theorist Dalibor Vesely. Images, according to Vesely and Benson, have their own power to launch interpretations. While this is not strictly the case, visual representations may serve as conduits for data that serve as proof of sharper and newer understandings. In science, nowhere have images been more effectively used as persuasive vehicles of scientific evidence recently than in making the case for human-induced climate change.
It is not accidental that the crucial allies in making this case have been cameras. Hadfield’s images show us the earth in ways we cannot otherwise see. Given the political and ideological obstacles to getting the public to understand the scientific case and evidence for climate change caused by human activity, images might in fact offer a more powerful approach. Hadfield’s photographs of the Arctic melt or of the shifting sand dunes in the Namibian desert, and another Benson project, a photo-essay that drew from NASA satellite photographs (an earlier installment of his engagement with astronomical images), including those from the satellites Aqua and Terra, have helped make the human impact on climate change more visible. Benson’s 2013 New York Times photo- essay “Gorgeous Glimpses of Calamity” ends with the following powerful plea:
Having constructed a civilization capable of observing our still paradisiacal world from objectivity-inducing distances, we need to set aside our squabbles, recognize that we face a species-wide threat, and use our scientific-technical genius to protect the only known home of life in the universe.
Benson’s photo-essay and Hadfield’s photos of the morphing planet are perhaps more persuasive in making the case for believing the science of climate change than the Intergovernmental Panel on Climate Change (IPCC) report that presents all the scientific data and results from measurements and mathematical modeling. Will these powerful images lead to action on climate change and to better stewardship of our planet and its resources? One can only hope.
What is the alternative? Failing to confront the danger of climate change collectively as a species will no doubt get us to the brink—the exact spot where the recent science-fiction film Interstellar by Christopher Nolan starts. Set in the future, Interstellar describes the journey of mankind to find other habitable planets, a journey driven not just by the human instinct to explore but also by climate change that, left unimpeded, made the earth inhospitable.
At the beginning of the film, we find a depressing world in which blight has decimated all crops except corn, and dust bowls are growing rapidly. Our planet is in peril—while the human population desperately attempts to retain a sense of normalcy. Since our own solar system is not particularly promising, a former NASA pilot, Cooper (Matthew McConaughey), a widower who lives with his two children and father-in-law (John Lithgow), gets recruited by a now-underground NASA for a secret mission to seek other habitable planets.
The portal to a system of potential new habitats is a “wormhole” near Saturn that transports Cooper and his fellow astronauts, including Dr. Amelia Brand (Anne Hathaway), to the vicinity of a super-massive black hole aptly named Gargantua. Scientists know that such monster black holes exist in the centers of the most luminous galaxies in the near and far universe. A wormhole can be thought of as a rip in the fabric of space-time that connects two extremely distant points in the universe.
The wormhole in Interstellar, we are told by the senior Dr. Brand (Michael Caine), astrophysicist and leader of the NASA mission, has been created by an unknown alien intelligence. A couple of planets perilously close to this black hole (which is spinning close to the speed of light, 186,000 miles per second) are candidates for exploration. These candidate planets—Miller, Mann, and Edmunds—are named after the astronauts who set out to explore them.
The weakest link in this otherwise enjoyable movie is the rather contrived emotional situation—the allegedly fraught relationships between fathers and daughters. Abandonment, aspiration, and transferred ambition from father to daughter are teased out very ineffectually in the relationship between Cooper and his young daughter Murph and between the senior Dr. Brand and his astronaut daughter. Neither nuanced nor textured nor even sophisticated, these relations seem to have been inserted merely to provide some human interest to a fantastic tale of an intergalactic voyage of discovery.
Thus far it all sounds pretty standard for the space-science-fiction genre. But what makes Nolan’s Interstellar stand out is that one of its executive producers is Kip Thorne, a highly respected expert on general relativity and a professor of astrophysics at Caltech. No other scientist, except Carl Sagan, has had such a pivotal part in a Hollywood science-fiction film, from developing the script to serving as executive producer to collaborating on the visual effects.*
It was crucial to Thorne that “nothing in the film…violate the firmly established physical laws.” So everything you see in the film’s special effects and plot is scientifically possible, and some things are plausible, although occasionally they are highly improbable. As reported in Thorne’s new book on the making of the movie, The Science of Interstellar, the project sounds like a remarkable collaboration with the Nolan brothers (Christopher directed and his brother Jonathan wrote the script) and one that involved many master classes in general relativity from Thorne.
Christopher Nolan has had a loyal following after directing Memento, the Batman trilogy, and Inception, and he’s known for his mind-bending plots that rely on future-oriented conceptions of science that hover on the edge of the believable. What he takes one step further in Interstellar, however, is the technical feats involved in making it. Its producers had to generate a total of about eight hundred terabytes of data, which is about half of the entire information content from all of the holdings in the Library of Congress.
Thorne concedes that the science in Interstellar is “at or just beyond today’s frontiers of human understanding.” This is precisely what adds the creative and imaginative edge to the film, a willful and slick blurring of the lines between “firm science, educated guesses, and speculation.” How scientifically plausible is the scenario of Interstellar? To inject a dose of reality, here are some facts: with the best current technology that we possess, an expedition to the environs of our nearest star, Proxima Alpha Centuri, 4.24 light-years away, would take 100,000 years for a one-way trip. Even if we were to develop revolutionary new propulsion technologies that would permit travel at, say, one tenth the speed of light, it would still take forty-four years to get there. So we are talking about exploratory missions that exceed the human life span.
These also come with many other as- yet insurmountable barriers. An astronaut’s excessive exposure to radiation during the trip would be fatal—one of the many problems that remains to be solved. A wormhole would really come in handy. And this is where Thorne, who first proposed the idea of a wormhole to Sagan for his novel Contact in 1983, springs it again for Interstellar. By bridging two very distant locations in the universe, wormholes solve the problem of travel time between them. This theoretical construct, also known as the Einstein–Rosen (ER) Bridge, could exist in principle according to Einstein’s theory of general relativity; but no wormholes have been detected and none have even been inferred from any existing evidence.
General relativity predicts some weird phenomena in the vicinity of strong gravitational fields—black holes, for example—but such phenomena are extremely counterintuitive. Two that Nolan deploys to great effect are the dilation of time and the bending of light. The immense gravitational pull of a black hole slows clocks down, causing time to lapse at a different rate for observers near it compared to those that are beyond its grip. This is at the heart of the famous twin paradox, in which one twin who remains on earth ages faster than the twin who returns to earth after traveling through deep space or near a black hole.
In the movie, time dilation is dramatic near the black hole called Gargantua, and in its vicinity earth-time is slowed down by a factor of seven. General relativity also predicts strong deviations in the paths of light rays that stray close to black holes and wormholes. In the film, Gargantua and the wormhole both distort light in the most dramatic and breathtaking ways. And here is where Thorne’s collaboration with Nolan has produced remarkable effects. The visual rendering of the bending of light, or gravitational lensing, by the intense gravity of Gargantua and the wormhole portal has been exquisitely rendered with unprecedented accuracy. Every swirl and twirl of light rays that jump off the screen is scientifically correct. Thorne computed the mathematical equations that describe the bending of light as the basis for the film’s visual effects. To generate these effects, Paul Franklin and Eugenie von Tunzelmann and their team at the UK-based special effects company Double Negative had to develop ray-tracing software—a brand-new method of rendering was developed in order to capture the physics truthfully.
The results are magnificent and a sight to behold. So much so that after seeing the astonishing visualizations, Thorne noticed several new features in the light bending by black holes that had eluded him and other scientists. The revolutionary new images calculated for special effects for Interstellar showed scientists something they have never seen before in the mathematical equations. In a recent article titled “How Building a Black Hole for Interstellar Led to an Amazing Scientific Discovery” in Wired magazine, Thorne recounts his excitement on seeing the visualization, and he reports that he is now writing up the new discoveries uncovered by the film’s visualization team as scientific papers for publication in peer-reviewed journals.
So from Cosmigraphics to Interstellar we come full circle. It is not often that Hollywood supplies new data to scientists that provide insights and lead to new breakthroughs. Perhaps this is the closest we will ever get to Benson’s fantasy of images directly leading to discoveries.
The only other instance was Carl Sagan and his wife Ann Druyan, who finished the script for the movie Contact in 1980, which did not actually get made until 1997. Unfortunately Sagan died seven months before it was released. ↩