科学美国人60秒:Moon-Smashing Meteorite Recorded by Astronomers

The moon has taken its fair share of beatings, as its craters attest. And last fall the moon took the biggest impact we've ever seen, when a huge meteorite slammed into the area known as the Mare Nubium basin.
 
Spanish astronomers spotted the September 11th collision using a telescope network that automatically scans the moon. The impact vaporized rock and created a flash of light brighter and longer than any we’ve ever recorded on the moon’s surface.
 
The compact-car sized meteorite smashed into the moon at 61,000 kilometers per hour. The ensuing explosion had the force of 15 tons of TNT, creating a new crater 40 meters wide. Anyone on Earth who happened to be moon-gazing at the time would have seen a flash almost as bright as the North Star. [See video of the impact.]
 
The moon gets pummeled by space rocks more often than Earth does because it lacks our protective atmosphere. The friction from passing through this blanket of air burns up most incoming meteors, letting through only the largest ones. Without such a shield, the moon is defenseless. Poor moon. But hey—better it than Earth!

—Clara Moskowitz