When an asteroid hits Earth - level 1
An organisation makes a video. It shows an asteroid. The asteroid hits Earth. The group says that asteroids hit Earth.
There is a special system. It listens to big explosions. Between 2000 and 2013, 26 explosions were found. These explosions happened when an asteroid hit Earth.
NASA watches big asteroids. These asteroids are bigger than 1 kilometre.
Difficult words: organisation (group of people who work on something), Earth (our planet), explosion (when something breaks quickly into small pieces).