Small, metre-sized asteroids strike Earth every couple of weeks. They add to our understanding of asteroid populations, of fireballs and their makeup, but they aren’t a big priority when it comes to Planetary Defence because they pose no real danger.

The objects we are most concerned about are those ‘goldilocks asteroids’ that are large enough to do harm if they impact, and there are enough of them out there that we know, at some point, they will. The infamous Chelyabinsk impact in February 2013 and the Tunguska impact in June 1908 fall into this category, and when it comes to discovering these asteroids, there’s still a lot of work to be done.