Fifty years ago today, celestial observers went from seeing a man in the moon to seeing one on it.

Few achievements in human history equal what was accomplished on July 20, 1969, when American astronaut Neil Armstrong took that literal “small step” and metaphorical “giant leap.” Armstrong and his fellow astronauts Buzz Aldrin and Michael Collins were rightfully hailed as heroes.

Last week, returning to Cape Canaveral on the anniversary of the Apollo 11 launch, the 88-year-old Collins sounded like the unassuming, laconic astronaut he was 50 years ago as he reflected on the mission.

“Apollo 11,” Collins said, “was serious business. We, [the] crew, felt the weight of the world on our shoulders. We knew that everyone would be looking at us, friend or foe, and we wanted to do the best we possibly could.”

They did. And then some.

Global viewing was estimated at about 600 million, or about a fifth of the world’s population at the time. That’s an especially remarkable figure considering how many did not have televisions in that era.

The “friend” Collins mentioned was really the entire world. The foe, ostensibly Cold War rival U.S.S.R., was no doubt also watching, just as the world took note of Soviet space-race firsts.

The global audience, awed by the astronauts’ achievement, would forever consider space — and in a way, Earth — differently.

And in a sense, they could consider mankind differently because of the collective effort behind the mission.

Collins rightly focused on the crew behind Apollo 11, which included all of those who created NASA and contributed to its success.

Former President John F. Kennedy considered this, too, when in appealing to Congress and the country to commit to the space program he said, “In a very real sense, it will not be one man going to the moon — if we make this judgment affirmatively, it will be an entire nation. For we all must work to put him there.”

And so the entire nation did.

Congress, representing the American people, made a funding commitment. NASA astronauts made personal commitments, while some — including Apollo 1 astronauts Virgil “Gus” Grissom, Ed White and Roger B. Chafee — lost their lives. (Others perished during Apollo-era training-jet crashes.)

Working alongside those wearing flight suits were engineers, technicians and several other sectors of specialists who made the missions possible. Notably, this largely behind-the-scenes team was more diverse than the high-profile crew of astronauts, as inspiring stories like the film “Hidden Figures” later explored.

After six missions to the lunar surface, NASA has not been back. And remarkably, no nation has repeated, let alone attempted, America’s feat.

President Donald Trump, like some of his presidential predecessors, has spoken of a return to the moon. But most of the actual effort and energy are from private entities, including high-tech firms or their billionaire owners.

Maybe, given the unresolved challenges here at home, that’s best.

But something is lost in the lack of a grand national program like that first moonshot. It brought out the best in America — and in humanity.