An impact large enough to de-orbit the Moon and send it crashing into Earth would clearly have to be bigger than any impact the Moon has ever endured in its past. Asteroids larger than 62 miles (100 kilometers) in diameter created the Moon’s largest impact scars, the Imbrium and South Pole-Aitken basins, almost 4 billion years ago.
How big of a meteor impact would it take to send the Moon careening into Earth?
Thomas Kumiega, Montville, Connecticut
