How big was the asteroid that killed all the Dinosaurs?

Question: How big was the asteroid that killed all the Dinosaurs?
- Keywords:
  asteroid,
  dinosaur,
  extinction,
  Life Science Centre
Asked by anon-271643 to Jake on 27 Nov 2020.
- Jake answered on 27 Nov 2020:
  
  Scientists estimate that the asteroid that killed the dinosaurs was nearly 10km across! Fortunately, asteroids that big don’t hit the Earth very often!

Question: How big was the asteroid that killed all the Dinosaurs?