Gene Cernan died today. He was the last man to walk on the Moon, as Commander of Apollo 17, in December of 1972.

Civilizations and empires, whether great or not, come and go. And the United States is still a relatively young country.

That said, of all the countries and empires and civilizations in the history of humanity and the men and women who lived in them, only twelve human beings have ever set foot on a surface that wasn’t Planet Earth. And they were American.

These twelve astronauts were all born in the 1930’s, and, as of today, five have left us. Reasonably, we should expect that the seven who remain – Buzz Aldrin, Al Bean, Edgar Mitchell, Dave Scott, John Young, Charlie Duke and Harrison Schmitt – will be gone over the next ten or so years.

One of the last things Gene Cernan did on the surface of the Moon was draw his daughter’s initials – TDC – in the dust of the lunar surface.

Those initials are still there along with Gene’s footprints.  They’ll be there long after we’re all gone, and for all time.

We don’t go to the Moon anymore. Some would say that’s okay, some would say it’s not.

But soon we will live in a world where no living person has walked on anything other than Earth.

So, when one of them passes away, I always feel like something is “a little bit more missing”, if that makes sense.

It makes me a little sad.