Exploring the Moon's Silent Craters

High above the Earth, a small robotic rover rolls slowly across the gray, powdery dust of the Moon. Its rugged metal wheels turn steadily, leaving tracks as it approaches the rim of a deep crater. Many lunar craters are large bowl-shaped pits formed when space rocks crashed into the surface. Some are billions of years old. By studying these ancient holes, scientists can learn what the Moon is made of and uncover clues about the history of our solar system.

Driving across the Moon is very different from driving on Earth. One of the biggest differences is the complete silence. On Earth, sound moves through the air as invisible waves of vibrating particles. When a car drives by or rocks crunch underfoot, those vibrations travel to our ears. The Moon, however, has almost no atmosphere. Because there is virtually no air to carry sound waves, sound cannot travel through the open space above the surface as it does through air on Earth. Even when the rover's heavy wheels grind against sharp stones, no sound can be heard across the empty landscape.