Where were you in 1972? That was the last time humans stood on surface of the Moon.

On December 14, 1972, Gene Cernan completed an adventure that Neil Armstrong started about three years earlier - he was the last man to step off the surface of Earth's Moon back onto Apollo 17. He and Harrison Schmitt then lifted off the lunar landscape and we haven't been back.

That was 42 years ago. Apollo 11 through Apollo 17 took a dozen men to the Moon (Apollo 13 had some troubles, if you might remember). It was an ambitious program, using technology that seems incredibly dangerous now, each launch sent three astronauts into space, with a spindly little landing craft that sent two of them to a landing and short stay on the moon. And, then they came back to Earth. Some people still don't believe it.

The Apollo program, at one point, was supposed to go through Apollo 20. But budget cuts and desires to build an orbiting space station dropped that number to Apollo 18, which was pretty much ready to go, but that was scrapped, too. Apollo 17 was the last mission. Geologist Harrison Schmitt was like a kid in a candy shop as they rode the lunar rover to interesting landscapes near the landing site. His work (and the rocks they brought back) has led to further discoveries of how the Earth and Moon system formed.

Orbiting robots have recently zoomed in to view most of the 40-year-old landing sites, which look pretty much the same, with rover tracks visible in the dust.

Tell your kids that today, December 14, is the anniversary of the completion of an amazing human adventure, when we visited the Moon.