Since humans landed on the moon 50 years ago, 12 people have walked on the moon, but no one has ever touched the surface.
The astronauts all wore spacesuits when they left the lander. No man has ever stood on the moon and taken off his gloves or boots.
As soon as we get inside and take off our spacesuits and gloves, we do have some moon dust on the floor and rocks that don't go in bags, Charlie Duke, an Apollo astronaut who walked on the moon in 1972, told me by phone. "On the way home, I collected some rocks that were floating around the spaceship. Anything that floats by, I pick it up and put it in my pocket. When I got back, I put them in a little jar the size of a prescription bottle and gave them to NASA."
Touching a moon rock in a spaceship or museum is one thing; Removing gloves and exposing yourself to the vacuum of space is another matter. In science fiction, terrible things happen to these astronauts: their blood boils and evaporates, and their guts are sucked out.
But removing a glove isn't immediately fatal. Most of the time, human skin is tough enough to cope with brief exposure to a vacuum. If you have a custom-made space suit with sealed forearms, chances are you'll be able to remove your gloves during the moon walk without permanent damage.
That must be uncomfortable. In 1960, air force colonel Joe Kittinger's pressure glove cracked during a high-altitude balloon test, exposing his right hand to near-vacuum conditions for several hours. His hand was swollen and unconscious, but he suffered no permanent damage.
That's what a vacuum feels like. What about the moon? Is it hot or cold?
It depends on where you stand. On earth, the hottest rock baked by the sun may reach 170 degrees Fahrenheit, but on the moon -- where the sun shines for weeks on end, never clouding and no breeze takes the heat away -- it gets hotter.
Apollo 16 landed on a lunar morning when the sun was low in the sky, but as the sun rose, the ground began to heat up. By the time they left, duke said, "the surface was over 200 degrees Fahrenheit." With two weeks of darkness on the night side and no air blanket, it can get colder than the South Pole in the middle of winter.
Surprisingly, the temperature of the dust isn't a big danger to your hands. Moon dust is a great insulator -- it's full of holes and cracks, and the lack of air prevents heat from moving from one part of the earth to another (or to your skin).
According to measurements of lunar soil and NASA guidelines for skin contact with hot objects, you can probably press your bare hands on the hottest lunar soil without feeling too hot.
But if your hand hits a rock, you may pull it back in pain. It's like taking hot clothes straight out of the dryer: even though the clothes are all at the same temperature, a lightweight, heat-insulating fabric feels warm and comfortable, but a dense, heat-conducting zipper will burn you.
I remember feeling the heat of the surface of the moon only once, duke said. As part of the experiment, the team exposed a metal shelf to direct sunlight for two days. "When I picked it up, I could feel the heat from the aluminum frame through the glove. That's not enough, well, to worry about; You just think, 'this is hot. '"
Moon dust may not burn you, but don't take it lightly. Like sand on earth, moon dust is actually made up of tiny pieces of glass, but the sharp edges have not worn away by erosion. Therefore, it can be quite dangerous.
But as long as you avoid touching rock or metal, wash your hands afterwards, and don't mind some temporary swelling, you could probably touch the moon and live.
Running barefoot may still be a bad idea.