It occurred nearly 40 years ago. Nearly everyone on the planet then remembers where they were and what they were doing. On the evening of Sunday, July 20, 1969, more than 1 billion people huddled around their TVs to watch the landing of a man on the moon. On the lunar plain known as the Sea of Tranquillity sat Eagle, the Lunar Excursion Module. Inside, pilot Edwin "Buzz" Aldrin Jr. performed duties on his checklist. Overhead, 70 miles above the cratered terrain, Command Module Pilot Michael Collins orbited the moon in Columbia, the craft that would eventually return the astronauts to Earth. But the world watched as Cmdr. Neil Armstrong descended from the Grumman-built LEM. And at 10:56 p.m., Armstrong stepped off the ladder. As his boot touched the soil of our nearest cosmic neighbor, he spoke words that will live forever: "That's one small step for a man, one giant leap for mankind." The world erupted in joy. A man was standing on the moon. There, Armstrong gazed upward into the black lunar sky at the sparkling blue and white globe he knew as home. That was the world from where stargazers of ages past had gazed skyward and dreamed of traveling to the stars. Nearly a century before, Russian space pioneer Konstantin E. Tsiolkovsky recognized our need to journey to worlds beyond. "The Earth is the cradle of mankind," he wrote, "but one cannot remain in the cradle forever." It was on that warm July night that we took our first steps from the cradle.