Asteroid impacts occur when a space rock, known as an asteroid, collides with a planet or moon. These impacts can vary in size, from small meteoroids that burn up in the atmosphere to large asteroids that can cause significant damage. The energy released during an impact can create craters and trigger environmental changes. The effects of an asteroid impact depend on its size and speed. A large impact can lead to mass extinctions, as seen with the Chicxulub impact that contributed to the extinction of the dinosaurs around 66 million years ago. Scientists study these events to better understand their potential risks to Earth.