A small asteroid shot towards Earth at 14.9 kilometres per second, and NASA admitted it did not know it was coming. The space rock known as 2019 MO was just three metres wide and exploded when it hit the planet's atmosphere on 22 July above the Caribbean, but the way it approached unexpectedly reaffirms the need for more eyes on the sky. NASA said: "When first spotted, 2019 MO was about 310,000 miles (500,000 kilometers) from Earth - farther out than the orbit of our Moon.

"This was roughly the equivalent of spotting something the size of a gnat from a distance of 310 miles (500 kilometres)."

Davide Farnocchia, a scientist at NASA's Center for Near Earth Object (NEO) Studies, said: "Asteroids this size are far smaller than what we're tasked to track.

"They're so small, they would not survive passing through our atmosphere to cause damage to Earth's surface."