Forty years ago this month I walked on the moon with Neil Armstrong and Buzz Aldrin. The odds are good that you did, too, if you were within the reach of a television or radio on that July 20. My family and 10-year-old self were vacationing on Cape Cod at the time, but my attention was mostly 230,000 miles overhead. With whelk shells in the silky white dunes, I rehearsed the lunar module's landing dozens of times along audacious flight plans that NASA would no doubt have discouraged.

For days I watched news anchor Walter Cronkite take America on tours of mission control and interview scientists and engineers about what the astronauts might find in the Sea of Tranquillity. Film clips recalled past fantasies of lunar exploration, from the French 1902 short Le Voyage dans la Lune to the 1950 classic Destination Moon. To this day, I remember learning about the Great Moon Hoax of 1835, which claimed that telescopes had seen bat-winged humanoids flitting through lunar caverns.

But even without bat people on the moon, the universe we were expanding into felt glorious. And that was why my family and I (and probably you and yours) cheered on that late Sunday afternoon when the Eagle lander touched down safely. That night I stayed up past my bedtime to watch every second of grainy televised footage of Armstrong and Aldrin on the lunar surface. Every detail of what I heard and saw after the “That's one small step for man” speech is a blur today and might have been at the time, too, because the overwhelming thought in my head was that we were on the moon.

That is why I have always felt that part of the absolute best popular science writing can do is to bring audiences along with the scientists and help them share personally in the adventure of those explorations, even if the scientists never wander outside a laboratory and the readers never wander outside a comfortable chair.

Twenty years ago this month I walked in the door and found a desk at Scientific American. It was both intimidating and exciting to be working at the source of such classic, inspirational articles as Harry J. Jerison's 1976 piece on comparative brain size and evolution, Alan H. Guth and Paul J. Steinhardt's 1984 essay on the inflationary theory of cosmology and R. W. Sperry's 1964 description of split-brain studies. After nearly 15 years as editor in chief, I still find it intimidating and exciting.

That is time enough for racking up accomplishments (and mistakes); for my own sake and Scientific American’s, I am taking another walk. But I am overjoyed that Mariette DiChristina, our executive editor for the past eight years, will be taking over for me: she will do a stupendous job of moving this magazine forward while protecting what makes it unique and valuable. Even if I had written this farewell differently, I would have lacked the space to express my gratitude and love for the colleagues here, past and present, who have supported, taught and befriended me beyond all bounds of duty. My last, best advice for anyone who seeks it is simply this: never forget what it meant when we were on the moon.