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Mark A. Garlick

Seeing black

The first image of a black hole, selected by Science as the Breakthrough of the Year, was both an amazing achievement and, for us, a daunting challenge.

For decades, black holes—collapsed stars with gravity so intense that not even light can escape—have been a subject of endless speculation. This image, produced by combining data from eight observatories scattered around our planet, became an immediate icon.

And that was the problem.

This bright ring, formed by light bending in the intense gravity generated by a stellar object 6.5 billion times more massive than our own Sun, had already been published thousands of times and viewed by millions, if not billions, of people.

Image of black holeEvent Horizon Telescope collaboration

What we needed to do was to come up with a concept that would freshly interpret one of the year’s most widely seen images. It had to be visually engaging enough to be cover-worthy, but also solidly rooted in science and current knowledge of black holes.

We spoke with Science’s editors and researchers about possible approaches. From those discussions, a question formed that shaped the visual concept: How would this unimaginably massive object appear to the naked eye from a nearby planet or moon?

The actual image created by the Event Horizon Telescope (EHT) could only hint at the answer. The EHT collaboration had observed galaxy Messier 87 (M87) with a global array of telescopes, collecting more data than any experiment in history. But their image of the giant black hole at the center of that galaxy was not seen as visible light but as radio waves emitted by the hot gas swirling around the black hole and invisible to the human eye. We had to make careful and accurate speculation about how such a thing would look to us.

Our initial design was ambitious—a spectacular view of the black hole (M87*) rising over dramatic atmospheric clouds. By placing the viewer in a world not unlike our own, this approach offered a way to present a profoundly alien object in the context of a familiar environment.

This first effort was influenced by the black hole depiction in Christopher Nolan’s 2014 movie, Interstellar. Although some artistic license was taken in its portrayal of a black hole, theoretical physicist, Nobel laureate, and black hole specialist Kip Thorne was consulted to make it as realistic as possible.

From conversations and information gleaned from a wide variety of articles, we developed an initial cover sketch.

Initial cover sketch for Science cover showing black holeA. Cuadra/Science

At the same time, we searched for an illustrator to create the final artwork. That led to U.K.–based artist Mark Garlick, who had extensive experience in creating space scenes. One of his illustrations, below, was very much along the lines of the initial cover concept.

Conceptual illustrationMark A. Garlick

Before moving further, we needed to check with an expert to validate our approach. Our initial research and brainstorming made us confident we were on a safe solid path to illustrate this view of a black hole. We anticipated a few minor adjustments, but no problem so major that we might have to rethink the entire illustration.

Of course, we were wrong.

We contacted University of Arizona’s Dimitrios Psaltis, project scientist at the EHT, who kindly agreed to help us check the science of our concept. We shared Mark’s illustration as a starting point.

The first thing Dimitrios pointed out was that most physicists in the field disliked or frowned upon the black hole depiction in Interstellar. “I complained multiple times to the Interstellar creators about spreading misleading information and offering it as ‘realistic’”, he said. Dimitrios explained that the accretion disk around M87* is very tenuous when it comes to visible light, and very thick. It would look nothing like the luminous disk crafted for the movie. He concluded that the accretion disk would be underwhelming to an observer.

The final blow to our initial concept was that the planet probably needed to be an airless rock. Although Dimitrios agreed that our hypothetical planet or moon could exist relatively near M87*, it was unlikely to have an atmosphere, as that would be blown away by the constant bombardment of high velocity particles coming from the black hole.

Without an impressive accretion disk or an atmosphere to support dramatic clouds, our initial concept was in peril. But then Dimitrios threw us a lifeline, noting that supermassive black holes like M87* have a spectacular feature—jets of matter heated to millions of degrees that flare from both poles. These jets are gigantic, larger, in fact, that the galaxy hosting the black hole.

Jet matter coming from the M87 black holeNASA, ESA and the Hubble Heritage Team (STScI/AURA); Acknowledgment: P. Cote (Herzberg Institute of Astrophysics) and E. Baltz (Stanford University)

Hubble space telescope image of the 5000 light-years in length jet of matter coming from the M87 black hole

 

A new approach began to form. From the lifeless surface of our imaginary planet one of these jets would dominate—a great sky river of plasma and radiation.

This new concept also suggested a possible animation. We imagined that we could show M87* rising in the horizon as the planet rotated, with the jet glimmering across the sky.

Once more we were wrong.

Dimitrios calculated how our imaginary planet might actually rotate. His figures suggested that the enormous gravity of M87* would bring the rotation nearly to a stop. A “day” on this planet would last for 2256 Earth days. With this glacial pace, our romantic notion of the black hole jet rising was impossible to sustain, crashing our rising black hole idea. The same way, the math showed that the jet would move extremely slowly, too much to be noticed by our hypothetical point of view.

Yet in the end, we were excited. The final illustration was not at all what we had imagined at the start of our journey, but solid scientific support helped us shed our misconceptions and develop a fresh view for Science’s readers of this amazing advance in our understanding of the universe.

The December 20, 2019 cover of ScienceMark A. Garlick

Alberto Cuadra is the Managing Graphics Editor at Science.