He walks through a principle most people miss: the relationship between Earth and space is not one-way. The cosmic ecosystem affects conditions on Earth in multiple ways, from climate forcing to the flux of debris entering the atmosphere. But the terrestrial system also feeds back into the cosmic one. The imprints of cosmic events are written into the geological record, into ice cores, into sediment layers. The primary vehicle for that interaction? The debris itself. We share near space with an almost inconceivably large population of material, remnants of comets, asteroids, and fragmented bodies moving through the inner solar system. That debris doesn't just pass by. It interacts, it impacts, it leaves a mark. Understanding that dynamic is essential to understanding how Earth's environment has changed over time, and how it will continue to change.