Imagine launching from Earth on a clear day, the kind perfect for liftoff. Through your window, the sky would transform before your eyes. It would blaze a vibrant blue, deepening as you ascended into the atmosphere’s dwindling air. Eventually, that blue would vanish entirely, leaving only the profound blackness of outer space to envelop your capsule.
Today, such observations are hardly controversial. It’s common knowledge that the daytime sky’s blue hue is an optical phenomenon, a result of sunlight interacting with our atmosphere. Astronauts have confirmed this firsthand, returning with accounts of space’s darkness. Yet, this understanding wasn’t always universally held.
So, who was the very first person to experience this transition? While Yuri Gagarin, the first human in space, might come to mind instinctively, a closer look reveals a more nuanced history.
Defining the Boundary
The initial question is simply: where does space begin? This, however, depends entirely on one’s definition of “space.” International aeronautical bodies, like the Fédération Aéronautique Internationale, conventionally set the lower limit at 100 kilometers above Earth, known as the Kármán line. Similarly, U.S. governmental and military organizations place this boundary at 50 miles, approximately 80 kilometers. These seemingly precise figures, interestingly, possess rather convoluted origins and justifications. The underlying principle, though, is that space commences where the atmosphere becomes too attenuated to sustain conventional flight, relying on aerodynamic or aerostatic lift.
Ultimately, these definitions are somewhat arbitrary. They don’t aim to delineate space itself but rather to define the capabilities and applications of specific technologies.
Beyond Conventional Limits
Alternatively, a more straightforward definition can be found in dictionaries. The Oxford English Dictionary defines space as “the physical universe […] beyond Earth’s atmosphere.” This seems simple, yet our comprehension of the extent of Earth’s atmosphere has evolved significantly over centuries. Current research indicates that it extends far beyond previous assumptions, with no atmospheric atoms remaining roughly 630,000 kilometers from our planet. No human has yet reached this vast expanse. NASA’s forthcoming Artemis II mission is slated to carry a crew approximately 7,500 kilometers beyond the moon—a historic feat that will surpass the Apollo 13 mission’s record, yet still fall more than 200,000 kilometers short of this expansive definition of space.
Despite these differing metrics, it would be illogical to claim the Apollo astronauts did not venture into space. However, considering the existing definitions, whether practical or scientific, there remains a missing element. What about a definition grounded in historical, cultural, or intellectual significance? Which definition of space holds the most meaning, even if it isn’t the most practical or precisely accurate?
Witnessing the Celestial Shift
From this perspective, one boundary emerges prominently: the point at which the atmosphere becomes too thin to refract sunlight, causing the familiar blue of Earth’s sky to yield to the dark void beyond. To grasp its importance, one must understand that for centuries, many Europeans believed space was a brilliant blue. They perceived the daytime sky as a direct view into this celestial realm. Unaware of the atmospheric optical effects, they attributed nightfall to Earth’s own shadow cast as the sun moved behind it, temporarily obscuring the blue universe. It wasn’t until the 17th century that scientists began to contemplate a dark universe, but the idea of a blue cosmos persisted in popular imagination well into the dawn of the Space Age, three centuries later.
In historical and cultural terms, a strong argument can be made that the first “astronaut” was the individual who ascended high enough to witness the sky turn black—the inaugural eyewitness to the truth that dismantled the ancient concept of a luminous cosmos. By the 1930s, high-altitude balloonists were already approaching this threshold.
Early Expeditions and Eyewitness Accounts
In 1935, the U.S. Explorer II, piloted by Albert Stevens and Orvil Anderson, achieved a record altitude of 22.1 kilometers. These early explorers experienced much of what Gagarin would later encounter. With nearly the entire mass of Earth’s atmosphere situated below them, they were protected from the harsh exterior environment by a pressurized gondola. They could observe the planet’s curvature on the horizon. Yet, above them, they reported to the surface that the sky, while “very dark indeed,” could still be described as “a very dark blue.”
A significant shift occurred in 1956 when Malcolm Ross and Lee Lewis piloted the Strato-Lab I balloon to an altitude of 23.2 kilometers. They maintained this position for several minutes before a malfunctioning valve forced an early descent. A U.S. Navy newsletter noted this as “the first time… the sky overhead was seen as black.” Just a year later, David Simons, piloting the Manhigh II balloon, also reported a “totally dark” sky at a comparable altitude of 22.9 kilometers.
While rocket-powered aircraft had previously reached similar altitudes, the very first person to do so might not have actually seen a black sky. In 1951, William Bridgeman reached 24.2 kilometers in a Douglas D-588-2 Skyrocket, an air-launched rocket plane. However, when questioned by the press about the sky’s appearance, Bridgeman, who only remained at his apex for a few seconds, admitted, “I’m not sure what colour the sky is. I think it’s dark, but I’m too damn busy to look out and see.”
Merely a month before Ross and Lewis’s flight, Iven Kincheloe piloted the Bell X-2 plane to an unprecedented 38.5 kilometers. His flight was similarly brief, and his visual observation was limited. Again, the press inquired about seeing a black sky, a clear indicator by that point that reaching this visual milestone was considered a benchmark for entering space. Kincheloe explained that he launched directly facing the sun’s “very searing white spot,” which caused the sky around it to appear “blue-black in colour […]. However, as we turned around and I had an opportunity to look down-sun, the sky definitely got blacker in colour—toward a kind of a definitely black inky colour.”
Kincheloe was also the first to ascend beyond 100,000 feet, another figure then cited as the boundary of space. His biographer even referred to him as the “first of the spacemen.” This distinction proved temporary. With the launch of the Sputnik 1 satellite in 1957, and particularly after Gagarin’s flight in 1961, the cultural understanding of visiting space shifted to reaching Earth’s orbit.
Experiencing the Hostile Void
While test pilots may have technically reached these altitudes first, the balloonists offered a more prolonged observation. David Simons spent over 24 hours in the stratosphere during his Manhigh II mission. From 30.9 kilometers above Earth, he meticulously documented the alien horizon, where “the atmosphere merged with the colorless blackness of space.” He was notably struck by the appearance of the stars. With minimal atmospheric distortion, they appeared as “untwinkling, living, colorful objects with places of their own in the cosmos and depth in an endless universe.” Simons considered himself to be in space, stating, “Our sealed one-man gondola was really a space cabin, hung from a balloon instead of nestled in the nose of a rocket.”
Another remarkable feat occurred in 1960 with Joseph Kittinger’s Excelsior III mission, a widely publicized jump from 31.3 kilometers above the planet. While the cameras on Kittinger’s gondola were focused downwards to capture the daring descent of America’s “new space hero,” Kittinger himself looked upward. “There is a hostile sky above me,” he reported. “Void and very black, and very hostile.” He returned from his flight profoundly affected by this perceived hostility, remarking, “Man will never conquer space. He may live in space, but he will never conquer it.”
Naturally, not all spaceflights commence during daylight. However, for those that do, experiencing the transition from our sky’s familiar blue to the blackness of space—however indistinct that boundary might be—remains a profound moment for astronauts, both military and civilian alike. In 2021, actor William Shatner participated in a Blue Origin flight, ascending to 107 kilometers. Following his journey, Shatner commented, “To see the blue colour go right by, and now you’re staring into blackness—that’s the thing.” While his flight crossed the Kármán line, officially placing him in space by modern standards, Shatner subjectively felt he had arrived when he witnessed the sky disappear.
The Kármán line represents an intellectual construct. The disappearance of the sky, however, is a visceral experience. Those who first witnessed this celestial shift could not have fully comprehended the profound historical significance of their encounter, marking the true end of the age-old perception of a luminous cosmos. Were they, in fact, the first individuals in space? In my view, their claim is at least as compelling as Gagarin’s.