Understanding the Near Earth Object population is a key component of planetary defence. Telescopic surveys are near complete for >200m sized bodies, but even metre sized objects are capable of posing a threat to people and property. The increasing number of manmade objects in orbit around the Earth is also becoming a concern and not all re-enter in a controlled manner. When objects hit the Earth's atmosphere, they produce light, heat and shock waves. Observing these phenomena, gives us a huge amount of information about the impacting object, be they natural or manmade. We can calculate the orbit they came from, what they're made of, their size, and even where any debris or meteorites might land. The Global Fireball Observatory is a planetary-scale observational facility for rare, fireball events occurring when objects hit our atmosphere. Multi-sensor observations allow us to characterise these objects, underlying planetary defence efforts.