It has been a great week for humans banging on things around the solar system. Japan’s Hayabusa2 probe touched down and grabbed a sample of asteroid Ryugu; NASA’s InSight is hammering into the surface of Mars; and a private Israeli spacecraft named Beresheet is heading toward an April landing on the Moon. But we are just beginners at the game. Nature has been banging and moving things around in the solar system for billions of years–and doing it with impressive efficiency.
Case in point: a rock nicknamed Big Bertha, and officially known as NASA catalog #14321. It was collected during the Apollo 14 mission by astronaut Alan Shepard, who picked it out because it contained an unusual-looking fragment. His instincts were spot-on. That chunk of Big Bertha really isn’t like the surrounding Moon rocks, most likely because it did not originate there. According to a study by David Kring of the Lunar and Planetary Institute and his colleagues, the fragment actually started out on Earth.
