Dear Humans,

Because the Moon has no wind or liquid water, Buzz Aldrin’s bootprint will probably be there for a long, long time. (Though a meteorite could smudge it.) Here on Earth, our footprints are often gone almost as soon as we make them. 

But imagine if they weren’t. Only 12 people have stepped foot on the Moon. Here on Earth, we’ve had somewhere around 100 billion people walking around on two feet. That’s a lot of footprints! Picture the mess we’d have if they hung around forever.

But do not fret. There are other ways to leave your mark here on Earth, long after all of your footprints have been erased.

Sincerely,

Mr. Curt