In 1920, a farmer named Jacobus Hermanus Brits was plowing a field in Namibia when his ox-drawn plow screeched to a halt against something buried inches beneath the soil. He had struck the Hoba meteorite, a roughly 60-ton, nine-foot-square slab of iron-nickel alloy that remains the largest intact meteorite ever found and has never been moved from where it fell. This episode investigates the puzzle it presents: an object that massive falling from space less than 80,000 years ago should have carved a crater like Meteor Crater in Arizona, yet there is none.

The answer lies in Hoba's unusually flat, tabular shape, which gave it a drag coefficient around 1.3 and turned its atmospheric entry into a cosmic belly flop, bleeding speed from more than 10 kilometers per second down to a terminal velocity of roughly 2.75 kilometers per second. Because k ...