BEIJING — Between 100,000 and a million small-scale asteroids have a possibility of hitting Earth over the next century, and five in particular have a collision risk of one in 1,000, according to Chinese astronomers cited by The South China Morning Post.


Although these asteroids are under 100 meters wide, much smaller than the asteroid that killed the dinosaurs, they remain a serious threat as they carry more kinetic energy than atom bombs.


In 2013 a 19-meter-wide asteroid exploded over the Russian city of Chelyabinsk, an explosion around 30 times as powerful as the nuclear blast over Hiroshima.


The damage to around 7,500 buildings and 1,500 people that one caused has been used by astronomers writing in the Acta Astronomica Sinica journal as an example of why we should be wary of these smaller space rocks.


Data in one existing database showed orbiting behaviors of more than 700 asteroids could propel them towards Earth in the next century, but physical models on asteroid formation calculated the number could range from 100,000 to a million.


The small size and large number of these short-term hazardous asteroids make them extremely difficult to track, according to the astronomers.