Here’s the big difference: An iron asteroid (like the one that formed Meteor Crater in Arizona) is dense enough to punch through Earth’s atmosphere and hit the ground. A comet fragment or low-density body (like Tunguska in 1908) explodes mid-air—flattening 80 million trees, but leaving no crater at all. That means atmospheric blasts are far more common than the craters we can count. Most impacts never leave a scar on the surface… but they can still unleash destruction. | The Randall Carlson