AN ASTEROID capable of causing catastrophic damage could come hurtling towards earth - and we wouldn’t have time to prepare for impact.

The worrying observation came as NASA’s planetary defence officer Lindley Johnson told reporters there was only a “limited” chance of spotting certain asteroids.

It means a space rock could crash into earth with little warning.

Mr Johnson told Metro that ground telescopes were used to look at the night sky, and if an asteroid approached from the ‘day side’ of our planet, the sun would blind us from spotting it.

“If the object is coming into the inner solar system and approaching Earth from the night side… our chances are pretty good of picking up objects of almost any size as they come close to Earth,” Mr Johnson told Metro.

“The smaller it is the closer it would have to come to earth for us to detect it.”

This was the case earlier this month when a 1.8 metre asteroid slammed into Botswana, Africa.

NASA had only detected the rock, named 2018 LA, hours before as it hurtled towards earth at about 61,115km/h. Thankfully, its small size meant it was a small threat, and it in incinerated as it plunged towards a farm in the small African nation.

But according to Metro, if the asteroid was larger, it could have potentially wiped out cities.

Mr Johnson explained that if a space rock came crashing towards earth on the ‘night side’, the chances of detection were significantly higher.

“If the object is coming into the inner solar system and approaching Earth from the night side… our chances are pretty good of picking up objects of almost any size as they come close to Earth,” he told Metro.

“But we have a vulnerability from the day side if asteroids have already had their closest approach to the sun, which is called their perihelium, then coming back out of the Solar System and approaching earth from the day side our capability to detect them ahead of time right now is very limited.”

No earth-destroying asteroids are believed to be plummeting towards our planet, but their have been some close calls in the past.

A 20-metre-wide meteor exploded in the air above Chelyabinsk, Russia, in 2013 that injured 400.

And in 1908, a 190-metre-wide asteroid ploughed into a Siberian forest. But if it had have hit a populated area, it could have killed millions.