Look into the night sky, and the achievement is mammoth. Fifty years ago, the country landed two men on the moon, Apollo 11 completing a journey that was a technological and scientific marvel. The three-member crew returned safely, just as President Kennedy had defined when he called for accomplishing the feat within the decade.

Actually, as many commentators have recalled lately, the mission belonged to more than Americans. The entire planet watched as the images arrived from the moon. In that way, Neil Armstrong, an Ohioan and the first man to touch the lunar surface, aptly chose his words about “a small step” for man and “a giant leap for mankind.” The world fixed its attention, and thought: We have done it.

Why did we go to the moon? There is the drive to explore, this continent once viewed as the new world. Kennedy described his administration as the “new frontier,” and outer space fit the description. Yet more than anything, the mission was about winning a competition — the space race.

Recall the jolt the country felt when the Soviet Union sent the Sputnik satellite into orbit in 1957. Americans feared they had fallen behind in the Cold War, that the Soviet adversary had seized a decisive advantage. The Soviets proved formidable competitors. They sent the first man into space, the first woman and multi-member crew. A cosmonaut conducted the first spacewalk.

The competition wasn’t about prevailing at stages. Kennedy raised the ante. The winner would be the first to reach the moon. So it is worth celebrating the achievement. Yet it is about more than coming out on top.

By 1972 and the last manned mission to the moon, 12 Americans had set foot there. They brought back 842 pounds of moon rock. In the process, those at NASA and its partners exhibited daring, know-how and extraordinary problem solving, for instance, the rescue of the troubled Apollo 13. There were setbacks. Yet those episodes, devastating as some were, in particular, the fire in the Apollo 1 capsule that left three astronauts dead, were learning experiences. They tested the necessary resilience, imagination and ambition.

That spirit is part of the legacy, and so are the many technological innovations, driven largely by public investment. There also was a public confidence in government, though it was starting to unravel as Apollo 11 landed on the moon, the country divided over the Vietnam War with Watergate around the corner. The space program advanced — through unmanned missions to fellow planets in the solar system, satellites that bring us such things as GPS and sophisticated weather and climate analyses. The space shuttle conducted 135 missions (two tragically flawed, 14 astronauts dying). The twin Voyagers are now more than 11 billion miles away.

What next? SpaceX and Boeing have plans for crewed missions soon. Jeff Bezos of Amazon sees his Blue Origin taking tourism into space. At one point, there was a rough NASA timetable for man traveling to Mars, covering 20 months. Virtually every White House since then has talked about such a journey, including the Trump administration, which has the idea of returning to the moon as part of testing and preparation. So there is private interest, plus other countries, China having set down a lander on the far side of the moon.

Yet in discussing the legacy of Apollo 11, something profound resonates in the images of Earth from that unique vantage, surrounded by dark space, small and vulnerable. They helped launch the environmental movement, and now 50 years later, they reinforce our obligation to preserve and protect what we have, space, a place to explore, Earth, our place to live.