asteroid
© NASA . JPL-Caltech
The agency said that it has detected and flagged bigger asteroids than the one in question. It has also confirmed that it was sure the space rock would do no harm as it wouldn't survive entry into the atmosphere.

NASA has detected but not taken measures against an asteroid that entered the Earth's atmosphere and exploded over the Caribbean.

The space agency admitted in a statement that the rock, measuring about 5 meters in size and designated 2019 MO, was first spotted when it was about 500,000 kilometres from Earth, just before it hit the atmosphere.

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

It was still flagged and reported to the NASA-funded Minor Planet Centre, which deals with data about the asteroids and comets, but was deemed too small to cause any damage to earthlings.

The fireball breached the atmosphere over the Caribbean in the evening of 22 June and burned up there, generating energy equivalent to roughly 3 to 5 thousand tons of TNT, according to astronomers.

NASA then analysed the explosion and traced it back to 2019 MO.

"Asteroids this size are far smaller than what we're tasked to track," said Davide Farnocchia, from the Centre for Near Earth Object Studies. "They're so small, they would not survive passing through our atmosphere to cause damage to Earth's surface. But this event shows how capable our search programmes are, even for objects of such small sizes."

NASA has recently warned that a "potentially hazardous" asteroid bigger than the Eiffel Tower would hurtle past Earth on Friday.

And in July, a mammoth space rock dubbed 2019 OK buzzed by at an "uncomfortably close" proximity, with scientists saying collision with Earth would be tantamount to the explosion of a "very large nuclear weapon."