An estimated 125 to 150 million Americans watched the Apollo 11 moon landing in 1969. Nearly half of the country's 57 million TVs were tuned to CBS, to Walter Cronkite, with former astronaut Wally Schirra at his side.

"Oh, boy!" Cronkite said after the Eagle touched down in the Sea of Tranquility. "Wally, say something, I'm speechless!"

"Oh, boy!" Walter Cronkite gleefully announces man landing on the moon. CBS News

That moment without Walter? Inconceivable. But nothing could have spoken louder than his small, spontaneous gesture, his awe, far more powerful than today's HD histrionics and hand jive.

This was the Most Trusted Man in America, a tough, skeptical reporter's reporter, who had stared down death covering World War II, suddenly overwhelmed by what had just happened. A stand-in for you, for me.

"How easy these words are rolling off our lips now: man on the moon, a walk on the moon. And yet, to say the words and to stop just a moment to think about them still sends a shiver up and down the old spine," he said.

The American flag on the Moon. It had to be understood in the context of the Cold War as our delayed answer to the Russians sending a satellite into space first.

In 1969 we were as divided as we are now, over the Vietnam War, over civil rights. The moon landing? We could all celebrate.

Cronkite said, "The date's now indelible. It's going to be remembered as long as man survives."

To watch CBS News' coverage of the Apollo 11 landing and of the astronauts' taking their first steps click on the video player below.

I look at the old coverage now and see such innocence, such optimism. Where did it go? Has technology moved so quickly in 50 years, that we've forgotten the immensity of the achievement?

Walter Cronkite never did. He was an unapologetic booster of the space program.

Here is Walter showing off a device designed to teach astronauts how to walk on the moon:

CBS News

In 1985, his was one of four names CBS submitted when NASA planned to send a journalist into space. (Mine was, too!)

A year later, after the crash of the Space Shuttle Challenger, the project was canceled. By then, Walter had made it to the finals at the age of 70. I have no doubt that if that mission had gone forward, one way or another, Walter Cronkite would have ridden a rocket to the sky.

CBS News' Walter Cronkite with a model of the lunar lander. CBS News

Story produced by Amy Wall.