An asteroid the height of the Albert Hall could hit the planet in 2017, experts have warned.
The space rock known as 2012 TC4 is between 12 and 40 metres long - the height of the famous Kensington concert hall - and whizzing in the direction of Earth.
Scientists say there is a chance of it smashing into the planet, though it is expected to fly past.
"It has a 0.00055 per cent cumulative chance that it will hit," Judit Györgyey-Ries, astronomer at the University of Texas, told astrowatch.net.
"It is something to keep an eye on."
A blow from a 40 metre asteroid could be disastrous for some - though it would not trigger a Hollywood-style apocalyptic scenario.
A meteor that exploded over the Russian city of Chelyabinsk in February 2013, injuring 1,500 people and damaging over 7,000 buildings, was about 20 metres wide, according to reports.
Detlef Koschny, of the European Space Agency, told the website: "There is one-in-a-million chance that it could hit us.
"A 40m object would go through the atmosphere and make a crater, a 10m rocky object would be hardly noticed."
