Earth just had a 'close shave' with an asteroid - and no one saw it coming

An asteroid larger than a Blue Whale whizzed between the Earth and the moon. Photo / iStock

Some close calls are enough to keep you awake at night, especially if they concern huge chunks of flaming rock smashing into the planet.

Astronomers marked one such close shave at the weekend after an asteroid larger than a Blue Whale whizzed between the Earth and the moon - a hair's breadth in astronomical terms.

Brazilian sky watchers had only just discovered the asteroid, called 2016 QA2, the day before it zoomed by within 80,000 km of Earth.

That's less than a quarter of the distance between Earth and the moon.

Astronomers at the Sonear observatory in Brazil discovered the rock on Saturday 27th August, and estimate its size to be between 25 and 55 metres.

The upper end of the range would make it far larger than the object which exploded over Chelyabinsk in Russia in 2013, smashing windows and injuring more than 1,000 people.

The team at Sonear believes the asteroid has been travelling in an elliptical orbit around the sun, completing a lap of the star approximately once every 350 days.

But its orbit is more elliptical than Earth's, sending it slightly further out from the sun - around 1.2 times the distance from the Earth to the sun.

A network of telescopes is trained on the skies to watch for asteroids coming within striking distance of Earth.

While the majority of these near Earth objects (NEOs) pose little real threat to us, but astronomers are closely monitoring a number which are potentially hazardous.

An object the size of 2016 QA2 - as named by the Minor Planet Center - would certainly do significant damage at the local scale, it wouldn't be enough to wipe out civilisation.

For comparison, the rock which caused the Chicxulub crater - believed to be responsible for the demise of the dinosaurs - was about 10km across.

But the rock which hit Tunguska in Siberia in 1908, scorching forest and flattening trees across thousands of square miles, is believed to have been between 60 and 190 metres wide.

According to Space.com, an asteroid would need to be of larger than 1 km wide to have the force to wipe out humanity.