Over its long history, the Earth has been repeatedly struck by celestial bodies drifting through space. This is proven by evidence left on the planet’s surface: impact craters. The most renowned crater is located in Arizona, but there are plenty of others, ranging from small, harmless, recent ones to much larger examples, stretching over hundreds of kilometres and setting off climate changes that led to the extinction of many living species. How often does an object from outer space crash into Earth? What are the current odds of our experiencing a cosmic impact? And, above all, do we have the technology to avoid the same fate that put an end to the dinosaurs?

Ettore Perozzi works in the Elecnor Deimos team operating the ESA NEO Coordination Centre at the European Space Research Institute (ESRIN) in Frascati. He formerly worked at the Italian National Research Council’s Space Astrophysics Institute, the European Space Agency, the Astronomical Observatory in Paris, and Telespazio in Rome. Asteroid no. 10027 bears his name.