Fifty years ago this week, Ed White, an astronaut and former U.S. Air Force officer, stepped into the cosmos while NASA’s Gemini IV spacecraft quietly orbited Earth. He wasn’t the first human to do so—that honor belongs to Russia’s Alexei Leonov—but the achievement marked an important chapter in NASA’s history. The occasion helped pave the way for 375 additional spacewalks performed by various astronauts over the years, including 260 walks by U.S. astronauts.

During the nearly half-hour White tumbled through space, the experience moved him so deeply that he almost forgot to end his extravehicular activity (EVA); a handful of engineers communicating with White from ground control had to convince him to get back into Gemini.

“I feel like a million dollars,” White said after first stepping out into space. “This is the greatest experience; it’s just tremendous.”

White later said that stepping back into the spacecraft was the saddest moment of his life. And who can blame him? Who can resist such a view?

Gemini IV’s mission didn’t initially call for a spacewalk. Instead, the plan called for White to simply poke his head out of a hatch, while another astronaut, James MvDivitt, held onto his legs. But one week before the spacecraft’s launch, a decision was made for White to go full EVA, partly in response to Leonov’s spacewalk, which occurred two months earlier.

What’s particularly interesting about White’s EVA, however, wasn’t just the fact that he successfully completed it; it was his reaction, later dubbed “space euphoria.” The condition, such as it is, is characterized by the feeling an astronaut gets when peering down at Earth from orbit, particularly when outside of a spacecraft. Imagine the flittering happiness you get from peering at the Earth’s surface from a commercial aircraft. Now imagine what that’s like from space.

There are several similar conditions comparable to space euphoria, as noted by Atlas Obscura, only experienced in extreme conditions. Divers, for example, experience something known as “nitrogen narcosis,” while some aviators have described a heightened sense of power due to the “break-off phenomenon.” Space euphoria is something only a small fraction of humanity has had the pleasure of experiencing.

Although White’s case of space euphoria was downplayed as “mild,” he actually spent so much time out there that his oxygen supply was nearly used up. McDivitt later revealed that he was under strict orders to cut White loose had he passed out while going full EVA. Frightening—but likely something White hardly even noticed.

Perhaps this feeling of euphoric existentialism is what drives humans to explore in the first place, to discover new lands, travel to different countries, be untethered by today’s hyper-connected world.

It’s why images like Pale Blue Dot are still so profoundly stirring. We should all strive to be Ed White.