NASA recently announced that the most powerful meteor strike since Chelyabinsk occurred in early February 2016 exploding over the Atlantic Ocean. Nobody was harmed, so why should we care?
It turns out that this small asteroid (probably less than 10 meters across) yielded an energy equivalent to about 12 kilotons of TNT as it exploded, making it just a bit weaker than the Hiroshima atomic bomb (although, with no radioactivity). The Chelyabinsk meteor, only twice the size of the Feb 2016 meteor, yielded more than 40 times this energy. We know that explosion caused over 1,000 injuries.
So we now know that small asteroids are potential killers. The problem is that they are difficult to discover they enter Earth’s atmosphere. Being so small and giving off only reflected light from the Sun, they easily avoid detection.